This article describes an action research (AR) project for designing and implementing a structured mentoring programme in a Spanish university. A student affairs unit, a team of researchers, faculty-mentors and student-protégés worked together on three cycles of AR. The result is a programmatic mentoring programme for the development of non-technical personal and professional competencies for undergraduate students. This paper describes the original situation that sparked the project, the iterative process followed, the tools and guides developed and the final programme designed. In addition to the increase in the level of satisfaction perceived by the entire university, the paper outlines the five critical factors that emerged from the AR project: the competency development process, programme value added, trust between mentors and protégés, the prominence of the student-protégé in the improvement plans and the continuous improvement culture generated.