Purpose: This study aims to examine the relationship between work engagement and leadership styles in human service organizations (HSOs). Specifically two leadership styles are investigated that are: participative and instrumental leadership style. Design/methodology/approach -- A questionnaire was used for data collection, and analysis of data were carried out using descriptive statistics and regression analysis. Findings: By examining workers (n=251) operating in nine HSOs in Italy, this study shows that the three dimensions of work engagement relate to leadership styles. The data analysis found that while the participative leadership style of supervisors is particularly significant in predicting vigour and dedication among employees, the instrumental leadership style is positively related to vigour and absorption. Research limitations/implications: The study has some limitations that could represent stimuli for future research. The analysis is cross-sectional, and variables were measured using a common method and source. Furthermore, since the study involves only a small number of Italian HSOs, the results cannot be generalized and must be interpreted accordingly. Practical implications: The findings from this study give rise to implications for the development of employees' engagement in HSOs. It additionally provides useful suggestions on effective leadership style among supervisors in HSOs. Originality/value: An important contribution of the present study to current debate on work engagement is an insight into the construct of leadership styles as antecedents of work engagement. Furthermore, support is provided to the current debate that calls for a multi-dimensionality of work engagement and therefore suggests that the three dimensions may be differently affected by the antecedents. A third contribution is a greater understanding of ways to manage human resources in HSOs through the lever of leadership style.