Geoscience education is, itself, a dynamical sub-system in the science, technology, engineering and mathematics (STEM) learning ecosystem. Both the larger STEM environment and the geoscience ecosystem are shaped by the ever-changing relationships among people, places, science content (and its communication), teaching practices, and shifting roles for each of these. In answer to calls in the literature for research on professional learning in which the faculty member is central to the process of change, the study reported here addressed the question: What is the nature of college science faculty readiness for change in instructional practices? The setting was a professional development experience in oceanography/marine science and paleoclimatology among 32 faculty from 2- and 4-year colleges. Ten of the 32 participated in interviews and all provided survey responses and documents used in analysis. Qualitative research methods resulted in three example cases to illustrate a new framework for exploring faculty readiness for professional change in teaching. This framework blends the Clarke and Hollingsworth (2002) model of a professional change environment with research from health sciences on readiness for behavioral change (Dalton & Gottlieb, 2003). From the first model came the multi-part foundation of personal, external, professional, and consequence domains of experience and from the second came how an instructor draws on those domains to: (a) see an instructional challenge as requiring intentional action to be resolved; (b) notice new significance (for the instructor) in some aspect of instructional practice; (c) feel able to manage instructional stressors/challenges; (d) have commitment to initiate/sustain change; (e) perceive adequate support in undertaking change. Three profiles of readiness for change are represented by three composite instructor cases named Lee, Pat, and Chris. In the case of Lee, factor c drove change efforts, for Pat, factors a and b were in the forefront, and for Chris it was factors d and e. Building a healthy learning ecosystem includes attention to faculty as learners. The three cases are valuable both as illustrations of the framework in use and as touchstones for future research and development related to post-secondary professional learning for teaching.