Preparation of new teachers to work effectively in inclusion settings has not kept pace with demands created by recent reforms. General-education candidates typically receive limited exposure to inclusion strategies at the preservice level, and often their only meaningful preparation comes in the practicum setting. The purpose of this article was to examine the manner in which characteristics of cooperating teachers and the practicum settings affected efficacy for teaching students with disabilities. General-education student teachers responded to questionnaires about their collaboration with cooperating teachers, the focus on inclusion instruction in their practicum setting, and their efficacy for providing inclusion instruction. Results from a structural equation model indicated that efficacy is predicted both by focus and by collaboration with the cooperating teacher. Discussion focuses on implications for teacher preparation and directions for future research.