Interdisciplinary teams for the treatment of child abuse and neglect are becoming more common. Studies have shown that decisions made by groups who have had the opportunity to discuss their perspectives are more accurate than judgments made by individuals. Why this may be true is not clear. The purpose of the present study was to discover the procedures an interdisciplinary treatment team uses in making decisions. A single interdisciplinary incest treatment team was observed over a 15-month period. Open-ended interviews with team members also were conducted. Findings show that the interdisciplinary treatment team made its decisions using procedures analogous to procedures used in social research to establish reliability and validity. The decision-making process of the team was characterized by multiple observations of family members by multiple observers in multiple settings over time. This decision-making process is similar to processes used by many other treatment teams. The findings of the present research, then, are likely to be generalizable to other teams whose decision-making processes are similar.