Fundamental Interpersonal Relations Orientation (FIRO) is a theory developed by Dr. Will Schutz in 1958 to explain human interaction. It can be used for individuals or groups and is especially useful for settings like drop-in centers. FIRO posits that everyone has needs for inclusion, control, and affection in interactions. Dr. Schutz later created the FIRO-B assessment tool to measure these interpersonal needs between two people, which became widely used for training purposes.