Abstract
This articlepresents the Group Leader Self-Eficacy Instrument (GLSI., which measures counselor trainees' self-eficacy for performinggroup leader skills in training groups, Foundation of the GLSI based on group theory, counselor training practice, and research is described. Development of the GLSI through replicated factor analysis is detailed, and evidence for the reliability and validity of the instrument is presented. Based on the single factor structure of the GLSI, an integrated approach to teaching group leadership is recommended.