This study documents the views of effective professional development held by eight professional development (PD) providers, representing four informal science institutions (ISI) and four programs within two institutions of higher education (IHE) in a large midwestern metropolitan area in the United States. This study finds that, while the reported learning and outcome agendas of the providers were similar across the board, a dichotomy in approach to PD emerged according to the type of institution. This dichotomy between ISI and IHE was persistent across thematic categories: (1) language use and meaning, (2) teacher outcomes as a result of PD, (3) resource strengths for teaching and learning, and (4) determination of content and course offerings. The significance of this research is threefold. First, the identification and characterization of important features of teacher PD in ISI is an important contribution to the PD literature, since most previous studies focus on IHE. Second, this study elucidates important differences between the two types of providers with respect to their views of inquiry, currently a fundamental component of PD for science teachers. Third, previously unreported gaps and overlaps in belief systems of PD from two institutions types, ISI and IHE, are identified. © 2007 Wiley Periodicals, Inc. Sci Ed91:604–628, 2007