This article focuses on collaborative relationships between contractors and government agencies and explores which contract characteristics, contractor traits, and environmental factors are associated with the development of such relationships. The study uses data from the Partnership Impact Research Project, a three-round longitudinal survey of over one hundred child care centers and Head Start agencies in Ohio. Our findings suggest that stronger collaborative contracting relationships are associated with greater contract specificity, better contractor service quality, and contractor affiliation with a larger organization. On the other hand, a contractor’s financial autonomy and nonprofit status are negatively related to collaborative relationship strength. We also find that a contractor’s internal management capacity is positively associated with the development of shared procedures governing contractual relationships.