Women with substance use issues and their children have unique needs that are best met through collaborative and coordinated service delivery offered by a variety of agencies. However, in Canada and elsewhere, services tend to be fragmented and fail to address children's needs. This study aimed to describe the partnership patterns, activities, and qualities among Canadian agencies serving women with addictions and to determine predictors of partnerships. We found that a number of partnerships exist, and that the extent and characteristics of these partnerships vary. Agency responsiveness to clients was predictive of sending referrals whereas friendliness predicted joint programming and consultation. Four central agencies played key linkage roles. Efforts should be made to build on the social capital inherent in these agencies to strengthen existing networks, further develop linkages to improve service delivery, and promote evidence-informed practice in a field where there is an identified research-practice gap. (Contains 5 tables and 1 figure.)