JOURNAL OF RESEARCH IN SCIENCE TEACHING VOL. 41, NO. 3, PP. 294–315 (2004) Implementation Variation and Fidelity in an Inquiry Science Program: Analysis of GLOBE Data Reporting Patterns William R. Penuel, Barbara Means BN 357, SRI International, 333 Ravenswood Avenue, Menlo Park, California 94061 Received 25 June 2002; Accepted 5 March 2003 Abstract: This article examines variations in patterns in the enactment of a large-scale kindergarten through Grade 12 science inquiry program. Student data reports in the GLOBE program provide a useful measure of implementation because key design elements in the program are student collection and reporting of local environmental data. We examined associations among teachers’ responses to survey items to patterns in GLOBE data reporting to develop hypotheses about important contextual factors related to program implementation. Implications for the study of science inquiry programs are discussed. ß 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 294–315, 2004 Researchers of educational innovations have long been concerned with studying variations in the implementation or enactment of educational innovations. Evaluators in particular have advo- cated the collection of data on within-program variability in program implementation, because the scale, depth, and fidelity of implementation cannot be assumed ahead of time when designing an evaluation (Patton, 1979; Rossi & Freeman, 1989; Scheirer, 1994). Data on variation in program implementation are critical both to understanding the limits of a program’s applicability or flexibility and to explaining within-innovation variations in effectiveness (Lipsey & Cordray, 2000). In addition, such data can help identify competing hypotheses for observed effects (Schiller, 2001) and possible flaws in the assumptions that underlie the program design (Goodson, Layzer, St. Pierre, Bernstein, & Lopez, 2000). Researchers differ in their interpretations of the significance of implementation variation. Some are concerned with measuring implementation fidelity—that is, the extent to which teachers enact innovations in ways that either follow designers’ intentions or replicate practices developed elsewhere (Loucks, 1983). These researchers often cite evidence from large-scale studies of innovations such as the Comer School Development Program, Success for All, and the New American Schools scale-up that implementation fidelity is often strongly related to program Contract grant sponsor: NSF; Contract grant number: ESI-9802033. Correspondence to: W.R. Penuel; E-mail: william.penuel@sri.com DOI 10.1002/tea.20002 Published online in Wiley InterScience (www.interscience.wiley.com). ß 2004 Wiley Periodicals, Inc.