The purpose of this study was to develop psychometric properties of the Peer Group Caring Interaction Scale (PGCIS) designed to measure caring during informal peer interactions as experienced by undergraduate nursing students. The PGCIS has two subscales that address caring peer behaviors and interactional events during which students assist their peers in the resolution of specific needs. PGCIS psychometric properties were developed using data from 873 junior students enrolled at 87 BSN schools of nursing. Internal consistency reliability was demonstrated for the 9-item Caring Behaviors and the 7-item Giving Assistance subscales with a coefficient alpha of .91 for each. Findings from an exploratory factor analysis supported the two subscale structure of the PGCIS. The PGCIS scores correlated positively with scores on the Intimacy subscale of the Organization Climate Description Questionnaire (OCDQ) and the Peer Group Interaction Scale and inversely with scores on the OCDQ Disengagement subscale. The findings from this study provide beginning support for the PCGIS as a valid and reliable approach to the measurement of caring in academic settings. Additional studies are recommended to continue the psychometric evaluation of this instrument.