Community ties with friends and relatives are a principal means by which people and households get supportive resources. Quantitative and qualitative data from the second East York study are used to evaluate six potential explanations of why different types of ties provide different kinds of supportive resources: tie strength, contact, group processes, kinship,network members' characteristics, and similarities and dissimilarities between network members in such characteristics. Most relatioships provide specialized support. The kinds of support provided are related more to characteristics of the relationship than to characteristics of the network members themselves. Strong ties provide emotional aid, small services, and companionship. Parents and adult children exchange financial aid, emotional aid, large services, and small services. Physically accessible ties provide services. Women provide emotional aid. Friends, neighbors, and siblings make up about half of all supportive relationships. The ensemble of network members supplies stable and adaptive support.