Previous research has linked inquiry-based science instruction (i.e., science instruction that engages students in doing science rather than just learning about science) with greater gains in student learning than text-book based methods (Vanosdall, Klentschy, Hedges & Weisbaum, 2007; Banilower, 2007; Ferguson 2009; Bredderman, 1983; Shymansky, Hedges, & Woodworth, 1990). The LASER model, being validated in the current study, has already been the subject of a number of case studies (RMC Research Corporation, 2010; Horizon Research, 2010; Vanosdall et al., 2007). However, experimental studies of the type that might establish a causal link between program implementation, student science learning, and other valued outcomes have yet to be conducted. Only a handful of studies have involved random assignment, and most of these have involved random assignment of students in a relatively small number of classrooms (see Furtak et al. 2009). With support from the U.S. Department of Education's Investing in Innovation Fund (i3), the current validation study of the LASER Model encompasses approximately 60,000 students, 1,900 teachers, and over 140 district administrators and principals. The efficacy of the LASER program has important implications for both research and practice when working with high-poverty schools and districts, who have limited resources and time available for science interventions. LASER's initial success with early learners also demonstrates its potential for reducing the development of chronic, long-term deficiencies and academic problems. One table and one figure are appended.