Mentoring student teachers during the practicum is a pivotal dimension of quality of teacher development. The key determinant of quality of mentoring is, however, the school mentor. This paper reports on a study, which examined the norms and standards that guided selection of school mentors in primary schools in the 1+ 1 Initial Primary Teacher Education Model in Malawi. The study employed a mixed methods sequential explanatory design comprising a survey followed by a case study. Data was collected from 92 mentoring primary schools with a total of 183 informants comprising 91 school head teachers and 92 school mentors. Quantitative data was analyzed by employing univariate analysis, and qualitative data was analyzed using content analysis. The findings revealed that school mentors were selected based on professional behavior, moral behavior, teaching experience, academic qualification, professional grade, age, school responsibility, mentoring experience and gender in order of decreasing frequency of use. A model of mentor selection anchored by the theoretical insights and the research findings is proposed.