Abstract: Increasing work engagement in a sustainable way remains a challenge despite years of research on the topic. Relationships at work are vital to foster engagement or disengagement. While the relational model by Kahn and Heaphy is conceptually appealing to explain work engagement, it lacks empirical support. Aims: The aims of this study were to investigate the associations among relational factors, psychological conditions (psychological meaningfulness, availability and safety) and work engagement and to test a structural model of work engagement. Setting: A total of 443 individuals in an agricultural research organisation participated in a cross-sectional study. Methods: Four scales that measured relational factors, the Psychological Conditions Scale and the Work Engagement Scale were administered. Latent variable modelling was used to test the measurement and structural models. Results: The results confirmed a structural model in which relational facets of job design contributed to psychological meaningfulness. Emotional exhaustion (inverse) and co-worker relationships contributed to psychological availability. Supervisor relationships contributed to psychological safety. Psychological meaningfulness and psychological availability contributed to work engagement, while emotional exhaustion contributed to disengagement. Conclusion: The relational context is an important target for intervention to affect the psychological conditions which precede work engagement. To promote work engagement, it is vital to focus on psychological meaningfulness, psychological availability and emotional exhaustion.