An effective Learning Assistant (LA) Program provides benefits for both Learning Assistants (LAs) and faculty, in addition to benefits for students. By analyzing LA and faculty reflections, weekly preparation sessions, and interviews with LAs and faculty, we can better understand the partnerships that develop between faculty and their LAs. We leverage a combination of qualitative and quantitative data to investigate the types of LA expertise and skills faculty value and how this affects the formation of these partnerships. The Preparation Session Observation Tool (PSOT), developed from this work, can be used by LAs, LA Program Coordinators, and faculty to reflect on the types of LA partnerships that emerge, and how these partnerships can be used in constructing effective learning environments. We anticipate that this tool can then be used to help LAs, coordinators, and faculty modify their working relationship to develop the type of partnerships that are best for their particular instructional setting. PSOT provides a finer-grained analysis to three broad partnership classifications that exist along a continuum: mentor-mentee, faculty-driven collaboration, and collaborative.