This brief presents new findings on the factors that are associated with fathers’ participation in Responsible Fatherhood (RF) programs. It is based on data collected for the implementation study of RF programs, which documents how the programs were designed and operated and identifies challenges and promising practices. It uses data from the PACT evaluation to describe the characteristics of fathers enrolled in PACT and the associations between the fathers’ characteristics and their program participation. The brief also explores variation in participation by programmatic differences. It concludes with a summary of common barriers to participation and suggestions for program providers about how to help fathers overcome these barriers. Because the data come from a select sample of four urban programs, the findings may not generalize to all RF programs.