The overall aim of present thesis was to study the use, feasibility and outcomes of a peer learning intervention for nursing students and new graduates, including studies using a quasi-experimental (Study I and III), descriptive (Study II) and mixed-methods (Study IV) design. Data were collected using questionnaires, observations, checklists for intervention fidelity, individual interviews and group interviews. When studying peer learning outcomes among nursing students, peer learning seems to have a significant interaction effect on self-efficacy, based on a comparison of changes over time between the intervention (n=42) and comparison (n=28) groups. Studying each group separately over time, significant improvements were found in the intervention group on thirteen of the twenty variables, whereas the comparison group improved on four (Study I). Observations of how nursing students (n=16) used peer learning revealed that the student pairs collaborated to different extents and in different ways. All students were observed practicing several competencies together (Study II). Testing the peer learning model in new graduates’ workplace introduction (n=10) revealed that new graduates’ descriptions of peer learning were consistent with the theoretical description (Study III). Feasibility was tested in relation to compliance and acceptability, and lessons were learned. In Study IV, fidelity to the intervention was generally good. When first-line managers (n=8) described their perception of using the peer learning intervention with new graduates, predominantly positive outcomes were expressed. When examining the effect of peer learning in workplace introduction for newly graduated nurses (n=35), it was difficult to draw any conclusions due to recruitment problems (Study IV). The conclusions is that peer learning is a useful model for nursing students’ that seems to improve self-efficacy more than traditional supervision does. The model gives nursing students opportunities to practice several competencies on each other, and these competencies, e.g., leadership and organizational skills are useful in their future profession. The students practice teaching and supervision skills on each other, which seems to be a natural part of the peer relationship. Peer learning in the context of new graduates’ workplace introduction describes in a way consistent with the theoretical description of peer learning outcomes thus, also here it seems as a useful model. When developing and testing new interventions such as peer learning, it is important to do so systematically to minimize problems when conducting an evaluation, where the MRC framework can be useful. First-line managers generally expressed a positive attitude toward the peer learning model.