Social networks play important roles in mental and physical health among the general population. Building healthier social networks might contribute to the development of self-sufficiency among people struggling to overcome homelessness and substance use disorders. In this study of homeless adults completing a job- and life-skills program (i.e., the Moving Ahead Program at St. Francis House, Boston), we prospectively examined changes in social network quality, size, and composition. Among the sample of participants (n = 150), we observed positive changes in social network quality over time. However, social network size and composition did not change among the full sample. The subset of participants who reported abstaining from alcohol during the months before starting the program reported healthy changes in their social networks; specifically, while completing the program, they re-structured their social networks such that fewer members of their network used alcohol to intoxication. We discuss practical implications of these findings.