Drawing on a conceptual model integrating research on training, work-family interventions, and social support, we conducted a quasi-experimental field study to assess the impact of a supervisory training and self-monitoring intervention designed to increase supervisors’ use of family supportive supervisor behaviors. Pre- and post-intervention surveys were completed, nine months apart, by 239 employees at six intervention (N = 117) and six control (N = 122) grocery store sites. Thirty-nine supervisors in the six intervention sites received the training consisting of one hour of self-paced computer-based training, one hour of face-to-face group training, followed by instructions for behavioral self-monitoring (recording the frequency of supportive behaviors) to support on-the-job transfer. Results demonstrated a disordinal interaction for the effect of training and family-to-work conflict on employee job satisfaction, turnover intentions and physical health. In particular, for these outcomes, positive training effects were observed for employees with high family-to-work conflict, while negative training effects were observed for employees with low family-to-work conflict. These moderation effects were mediated by the interactive effect of training and family-to-work conflict on employee perceptions of family-supportive supervisor behaviors. Implications of our findings for future work-family intervention development and evaluation are discussed. Drawingon a conceptual model integrating research on training, work-family interventions, and social support, we conducted a quasi-experimental field study to assess the impact of a supervisory training and self-monitoring intervention designed to increase supervisors’ use of family supportive supervisor behaviors. Pre- and post-intervention surveys were completed, nine months apart, by 239 employees at six intervention (N = 117) and six control (N = 122) grocery store sites. Thirty-nine supervisors in the six intervention sites received the training consisting of one hour of self-paced computer-based training, one hour of face-to-face group training, followed by instructions for behavioral self-monitoring (recording the frequency of supportive behaviors) to support on-the-job transfer. Results demonstrated a disordinal interaction for the effect of training and family-to-work conflict on employee job satisfaction, turnover intentions and physical health. In particular, for these outcomes, positive training effects were observed for employees with high family-to-work conflict, while negative training effects were observed for employees with low family-to-work conflict. These moderation effects were mediated by the interactive effect of training and family-to-work conflict on employee perceptions of family-supportive supervisor behaviors. Implications of our findings for future work-family intervention development and evaluation are discussed.