This study presents the determinants of trust in light of the scientific literature on trust and governance networks. The theoretical analysis focuses on differentiation of various types of trust and its determinants at both for-profit and nonprofit organizations. Moreover, the idea of a network is presented with the main attention given to the performance of collaborative service delivery networks. On the basis of theoretical study, a longitudinal analysis was performed at institutions providing services to the homeless people in Warsaw, Poland. During the periods of 2013 and 2017 to 2018, two cohorts of field questionnaire studies were conducted among employees of 18 social welfare centers (sample based on 18 Warsaw districts) and homeless shelters run by nonprofit organizations (samples of 19 and 22, respectively). These local government institutions and nonprofit organizations comprised the collaborative service delivery network under study. Mixed-method research was applied at welfare centers and nonprofit organizations (NGOs) where both frontline and management level employees were interviewed, and some data were statistically evaluated. The research was conducted using the same questionnaires at both points in time. The research showed that, from the perspective of social welfare centers, interorganizational trust in relation to other social welfare centers and to nonprofit organizations is positively correlated with perceived interorganizational effectiveness of other actors in the network (measured by the possibility of obtaining information, promptness, commitment, completeness and correctness of documents, and assessment of employees’ knowledge). The same results were obtained from the perspective of NGOs. In addition, these correlations remained almost unchanged over time, although the research was repeated after many years using the same variables. Finally, there is no basis to state that trust is correlated with outcome perception when considering the most difficult and complex social services.