In today’s era of new public management, respecting the dignity and worth of social workers in organizational management poses a challenge to social work agencies. This research explores whether individual self-actualization can be integrated with organizational development by using a humanistic management approach. Authors sampled 672 supervisors from Chinese social work agencies. A structural equation model was built and tested to examine the relationships between four latent variables: (1) professional competence (PC), (2) organizational citizenship behaviors (OCBs), (3) individual impact, and (4) organizational impact, taking into account the moderating effect of professional associations. The results indicate that individual impact is a mediator between supervisors’ PC/OCBs and organizational impact. Meanwhile, professional associations play a moderating role in the relationship between supervisors’ PC and organizational impact. Findings provide the basis for a humanistic management strategy for social work agencies that focuses on the individual impact of key people to maximize organizational impact. Moreover, professional associations should strengthen the link between individual impact and organizational impact.