Research indicates that mentoring programs help increase the retention of beginning teachers. School administrators may be presented with competing mentoring models, with various sources and types of support, aimed at improving beginning teacher retention. This study collected both qualitative and quantitative data under the rubric of a comparative case study method to investigate mentoring models in the Asher and Dane School Districts (pseudonyms). Using this approach, the authors explored the two distinct models related to beginning teacher retention. Although both districts used collaborative teams, in-school mentors, and principals within the context of professional learning communities to participate in the mentoring of beginning teachers, only the Dane School District employed district "coaches." Findings from this research suggest that these "coaches" were not as effective as in-school mentors or collaborative teams in increasing retention, possibly because of lack of proximity and personal relationship. Additional findings describe and explain mentoring characteristics and different sources of support that benefited the mentoring experience and subsequent retention of beginning teachers. (Contains 3 figures, 7 tables, and 1 note.)