R. E. Heyman and A. M. S. Slep developed and conducted an effectiveness trial of a diagnostic system for child and partner maltreatment. The current investigation tested the widespread dissemination of the diagnostic system at 41 child and partner maltreatment services sites (n = 549 partner maltreatment cases and n = 342 child maltreatment cases). Agreement between field and master reviewers' decisions was good for partner physical and emotional abuse (kappa = 0.83-0.84). Agreement was also good for child physical, emotional, and sexual abuse (kappa = 0.73-0.89) but lagged slightly for child neglect (kappa = 0.66). Thus, multifaceted and content valid family maltreatment diagnostic criteria can be disseminated reliably. Replication studies of interrater agreement of the diagnostic system in typical clinical and agency settings are necessary; however, the high levels of agreement in myriad field sites imply that consistency of maltreatment determinations is achievable in widespread use.