An estimated 60 000 employees in the NPO sector in South Africa are social workers (Skhosana 2020). However, because of job uncertainties owing to poor funding (Setati 2023). This sector is plagued by organisational commitment issues (Mujajati, Ferreira & Du Plessis 2024). Non-profit organisations that seek exceptional performance and the retention of human resources need a workforce that is committed to both the organisation and their job (Özdemir 2017). Servant leadership is one of the primary strategies NPOs can adopt to get employees committed to the organisation. However, the servant leadership construct has been widely researched (McQuade, Harrison & Tarbert 2021), and its impact on attitudes such as organisational commitment is limited, especially in the context of NPOs (Ngah, Taiwo & Ismail 2023). In this regard, this study examined the impact of servant leadership on organisational commitment in a selected NPO in South Africa. Given the limited research on the mechanisms underlying servant leadership’s effects on individual attitudes and behaviours, this study explored the mediating role of self-esteem in the relationship between servant leadership and organisational commitment.

This study is based on SET and SIT. The SET is one of the most recognised concepts for clarifying exchanges between individuals (Ng 2023) and it is crucial in explaining the development of commitment among employees. Social exchange theory posits that parties can be involved in reciprocal relationships that benefit each other. In essence, employees attribute human-like characteristics to their employers, reflecting how much they care for the workers’ well-being (Jelil Ladebo, Jacob Olaoye & Oyekale Adamu 2008). The employer–employee relationship is determined by employers’ perceptions of their benevolence, as reflected in the provision of favourable job conditions such as promotion, equitable policies and emotional support. Hence, an employee reciprocates positively when such favourable conditions exist. In the context of this research, servant leadership attributes such as sharing power, teamworking and an emphasis on employee well-being can elicit high levels of organisational commitment. In essence, employees’ commitment to the organisation represents a form of reciprocity. Hence, SET is a suitable theoretical underpinning for this study. On the other hand, the SIT proposed by Tajfel and Turner (1979) helps explain the development of self-esteem among employees. Social identity theory posits that people derive part of their identity – their social identity – from the groups to which they belong (Scheepers & Ellemers 2019).

Social Exchange Theory and SIT complement each other by explaining both relational and identity-based mechanisms linking servant leadership to organisational commitment via self-esteem. Social Exchange Theory suggests that when servant leaders provide support and care, employees feel valued, which enhances self-esteem and prompts reciprocity, leading to stronger commitment. In contrast, SIT explains how servant leadership fosters a sense of belonging and organisational identification, thereby strengthening self-esteem. Together, these theories show that self-esteem reflects both exchanged support and internalised organisational identity, thereby reinforcing commitment.

Greenleaf (1977) established the concept of servant leadership. It posits that leadership is exercised by first fulfilling employees’ highest priority demands. The servant-first character of servant leadership distinguishes this notion from other leadership theories, as the above anecdote illustrates (Lee et al. 2020). It prioritises meeting its followers’ highest needs, setting aside personal needs and wishes (Eva et al. 2019). Previous servant leadership research has primarily related leadership to employee attitudes and behaviours in the workplace (Dinc 2018), including the psychological atmosphere of the workplace (Jena, Pradhan & Panigrahy 2018). However, servant leadership research in for-profit organisations focuses on unit, group and team-level characteristics to examine its direct impact on employee attitudes and actions, as well as the mediating effects of organisational culture and climate (Qing et al. 2020). It is well recognised that servant leadership prioritises satisfying the needs of individual followers, and that, usually, a servant leader’s interaction with their followers is on an individual basis (Wu et al. 2021). However, the effects of individual-level servant leadership on employee attitudes and personal resources, such as self-esteem, have not been explored particularly in a non-profit organisational context.

Meyer and Allen (1991) defined organisational commitment as a firm belief in, and support of, an organisation’s goals, determination to apply hard work on behalf of the organisation, and a genuine desire to remain with the organisation. It has been linked to several positive individual and organisational outcomes (Mitonga-Monga, Flotman & Cilliers 2018). Organisational commitment is a three-dimensional construct which includes: (1) affective commitment (AC), (2) continuance commitment (CC), and (3) normative commitment (NC). Affective commitment, which entails exploring how employees identify with the organisation, their involvement, and how they are emotionally attached to their job (Gao–Urhahn, Biemann & Jaros 2016). It has been noted that employees with high CC continue to work in their jobs because they want to. Continuance commitment (CC) is a method of evaluating an employee’s commitment based on their capacity to assess the cost of leaving their job as well as the cost of changing employers (De Clercq et al. 2021). Several studies (De Clercq et al. 2021) have also reported that employees with a strong continuance commitment to their jobs tend to stay because they believe they would lose a significant amount if they left. Normative commitment (NC) is defined as a commitment founded on an individual’s obligation to their work and is unrelated to the employee’s emotional connection to their company (McCormick & Donohue 2019). In this study, organisational commitment will be reported as an outcome of the relationship between servant leadership and self-esteem, serving as a mediating variable.

In today’s world, the concept of self-esteem is ubiquitous. People often assume that high self-esteem is necessary for success in various settings, including classes, workplaces, sporting activities and music concerts (Vaughan-Johnston et al. 2020). Indeed, promoting and preventing low self-esteem is commonly regarded as a critical societal goal that requires extensive intervention to improve the population’s self-esteem levels. According to Peixoto and Almeida (2010), self-esteem refers to a person’s subjective assessment of their worth as an individual. Self-esteem has been linked to positive outcomes such as increased initiative, satisfaction and happiness. It has become increasingly evident that self-esteem is not only a significant psychological need but also an economic need and an employee’s cognitive and decision-making capacity. Individuals with high self-esteem have been reported to handle conflict situations, execute tasks independently and establish relationships with others (Harris & Orth 2020). An individual’s self-evaluation is mainly based on their interactions with others (Tan, Krishnan & Lee 2017). As a result, interactions with superiors or managers are likely to affect an individual’s self-esteem.

To concur with this notion, Shamir House and Arthur (2018) reported that servant leadership draws some of its efficacy from its effects on follower self-esteem. However, there is a paucity of studies in the literature, particularly in the South African context, that examine the effects of follower self-esteem on leaders. Following this point, the study uses self-esteem to reflect followers’ attitudes towards their leaders and followers’ attitudes towards themselves, respectively, and hypothesises it as a mediator between servant leadership and employee attitudes such as turnover intentions and organisational commitment.

A positivist approach was used in this study. This is essentially the belief that only ‘truthful’ data, generated through observation and scientific measurements, is trustworthy (Marsonet 2019). When using this approach, the investigator’s role is limited to data collection and interpretation, and an objective methodology is employed. In this type of study, the results are observable and quantifiable.

This study followed a quantitative descriptive method. This quantitative study involves the use of questionnaires to gather data for statistical analysis and reach a conclusion for the stated hypotheses (Creswell & Creswell 2017). Quantitative research is cost-effective and time-efficient This study utilised a cross-sectional survey because it enabled the simultaneous assessment of the research outcome (organisational commitment), exposures (servant leadership) and the mediating factors (self-esteem) to answer the research questions.

A population is referred to as all the elements that meet a set of specific criteria for inclusion in a study (Salkind & Frey 2014). The population for this study consisted of 420 non-managerial employees working at a selected NPO in the North West province of South Africa.

A simple random sampling method was used to select participants. A complete list of 420 individuals was created, with each person given a unique number from 1 to 420. Random numbers were generated in Microsoft Excel, and the list was sorted by them. The first 260 individuals from this randomised list were chosen as the sample. Sampling was carried out without replacement to ensure that each participant had an equal and independent chance of being selected for the study. According to Israel (1992) and Krejcie and Morgan (1970), a sample size of at least 201 employees is considered sufficient for the targeted population. However, 208 questionnaires were returned, yielding a response rate of 80%. The inclusion criteria required participants to be non-managerial employees with at least 1 year of experience in a selected NPO in the North West province of South Africa, and both male and female employees were eligible to participate.

According to Table 1, a total of 208 respondents took part in the study, and the majority (n = 124) of them were female. Most (n = 90) respondents were between the ages of 30 years and 39 years and were most likely to have a bachelor’s degree. Seventy-eight employees had served the organisation for 16 years – 20 years.

Discriminant validity reflects the extent to which a construct does not correlate with measures of theoretically different or unrelated constructs. According to Hair et al. (2012), discriminant validity can be assessed using the Fornell-Larcker criterion. This technique compares the square roots of the AVE values with the correlations of the latent variable with other constructs. To satisfy discriminant validity, the square root of the AVE of each construct should be higher than the correlation with any other construct (Hair et al. 2012).

Table 3 confirms that the measuring instrument meets the discriminant validity threshold, as each construct’s discriminant validity values exceed its correlations with other constructs.

This study sought and obtained ethical approval from the North-West University Faculty of Economics and Management’s Research Ethics Committee (FEMS REC). The ethical approval number is NWU-00940-20-A4. Respondents were not coerced into taking part in this research, as informed consent was sought before data collection. The collected data was stored in a password-encrypted database. All collected data will be disposed of within 5 years in line with the POPI Act, and NWU has established guidelines and procedures.

This study employed Harman’s one-factor test (Harman 1976) to assess common method bias (CMB). According to this test, no single factor should account for more than 50% of the variance among variables. The findings confirmed this criterion, as the strongest single factor explained only 29% of the total variance.

This study evaluated the predictive capabilities of the structural model through Q² values and its explanatory strength using R² and F² Effect Size measures (Rubel, Kee & Rimi 2020).

In SMART PLS, Q² is calculated using the blindfolding technique. As suggested by Chin (1988), Q² should be greater than zero (0). The Q² values were 0.15 and 0.13 for self-esteem and organisational commitment, respectively. This indicates that the model’s predictive accuracy was strong.

The R² was used to evaluate the model’s explanatory power. As shown in Table 4, servant leadership and self-esteem explained 56.6% of the variance in organisational commitment. However, self-esteem accounted for a greater explanatory contribution (0.619), whereas servant leadership accounted for 0.172 of the variance. On the other hand, servant leadership explained 51.5% of the variance in self-esteem. These results indicate a strong explanatory model.

According to Cohen (1988), f² values are interpreted as follows: values close to 0.02 = small, 0.15 = medium and 0.35 = large. Accordingly, servant leadership had the greatest effect size on self-esteem (0.294) and a medium effect on organisational commitment (0.172). Self-esteem had a fairly large effect on organisational commitment (0.220) (see Table 5). These results imply that exogenous variables had a significant explanatory power on the endogenous variables.

Structural equation modelling was used to test the hypotheses above, and the results are shown in Figure 2 and Table 6.

The job performance model of motivation emphasises the significance of job context (leadership styles) and individual factors, including ability, job knowledge, dispositions and traits, as well as beliefs, in determining individual performance and positive employee attitudes. We were interested in self-esteem as an important individual trait for organisational commitment. In line with the job performance model (Mitchell 1997), this contribution argues that contextual or situational variables (e.g. servant leadership) affect individual variables (e.g. self-esteem), which, in turn, influence employee outcomes (e.g. organisational commitment). This means that when evaluating employee performance, one must consider both situational and contextual factors.

This study concluded that servant leadership has a profound impact on organisational commitment and self-esteem. The study therefore recommends that NPOs inculcate a culture of servant leadership through leadership development programmes. Leadership development programmes build a knowledgeable pool of employees who are likely to have improved self-esteem. Furthermore, this study concluded that self-esteem serves as an underlying mechanism of servant leadership, influencing organisational commitment. In line with this, it is recommended that NPOs focus on building self-esteem among their workforces. This can be done through workshops or coaching sessions that focus on building confidence and self-worth. Furthermore, to improve self-esteem, NPOs must prioritise a culture of recognition and feedback, and provide opportunities for growth to promote self-esteem and hence commitment.

The theoretical significance of this study is manifold. Firstly, this study validates the SET. The significant positive relationship between servant leadership and organisational commitment implies a reciprocal relationship between employer and employee. This finding implies that employees in the NPO perceive their leaders’ benevolent actions positively, which, in turn, leads to their commitment to the organisation. Secondly, South African studies on servant leadership primarily focus on large corporations; therefore, this study extends the body of evidence on servant leadership to the NPO industry. Thirdly, although servant leadership research is well established, there remains a need for research exploring the mechanisms by which servant leadership and individual attitudes influence behaviours (Dahleez et al. 2021). This study, therefore, introduced self-esteem as a mediator in the relationship between servant leadership and organisational commitment.

The findings of this study have practical significance for NPOs. The findings suggest that managers who exhibit servant leadership behaviours can significantly enhance employees’ self-esteem, which, in turn, leads to higher organisational commitment. This indicates that adopting a servant leadership approach can be a strategic way to improve overall employee attitudes within the NPO. Non-profit organisations in South Africa face high turnover rates, which are attributed to poor leadership styles among other factors (Aboramadan & Dahleez 2020). Given the significant relationship between servant leadership, organisational commitment and self-esteem, organisations should evaluate leadership styles when hiring for managerial positions. Organisations should instead focus on hiring people for management positions who are empowering, encouraging, honest and servant-like. In addition, Greenleaf (1977) suggests that a servant leader has a natural desire to serve others. Servant leadership is an inherent quality within an individual, and individuals can therefore be trained to demonstrate this behaviour according to the behaviourist approach to leadership (Northouse 2016). Non-profit organisations must assess the extent to which current leadership cadres demonstrate servant leadership behaviour and develop training and development interventions to enhance their desire to serve. Organisations are more likely to experience favourable employee attitudes if these types of people are selected to fill management positions.

The study also confirms that a person’s self-appraisal of their worth also impacts organisational commitment. Self-awareness is also a key ingredient in leadership development programmes. Self-awareness contributes to both organisational commitment and employee performance. To support this, company leaders should implement self-awareness training that enables employees to better understand their feelings, thoughts and values. Investing in employee development programmes can enhance self-esteem and commitment, ultimately helping counteract high turnover in the NPO sector. Training initiatives that focus on emotional intelligence, self-awareness and skill development not only improve job performance but also strengthen employees’ confidence in their abilities, leading to greater organisational commitment.