This article used focus groups to explore Puerto Rican preservice teachers' perceptions of sources of self-efficacy. The present study allowed, through a qualitative design, examination of the experiences of preservice teachers at the end of their student teaching practicum. The qualitative design and the use of the focus group technique provided insight into the main sources of their perceived self-efficacy through the self-assessment of their field experience. The beginning of the student teaching practicum provoked an intense process of emotions in which the preservice teachers needed support and guidance, particularly in aspects of planning, differentiation, and classroom management. The participants agreed that substantial feedback and guidance from cooperating teachers and university supervisors helped them being confident and increased their perceived self-efficacy by reducing the feelings of anxiety generated by the practicum.