The purpose of this study was to assess the effects of small-group tutoring with and without validated classroom instruction on at-risk (AR) students' math problem solving. Stratifying within schools, 119 3 rd -grade classes were randomly assigned to conventional or validated problem-solving instruction (Hot Math [schema-broadening instruction]). Students identified as AR (n = 243) were randomly assigned, within classroom conditions, to receive Hot Math tutoring or not. Students were tested on problem-solving and math applications measures before and after 16 weeks of intervention. Analyses of variance, which accounted for the nested structure of the data, revealed the tutored students who received validated classroom instruction achieved better than tutored students who received conventional classroom instruction (ES = 1.34). However, the advantage for tutoring over no tutoring was similar whether or not students received validated or conventional classroom instruction (ESs = 1.18 and 1.13). Tutoring, not validated classroom instruction reduced the prevalence of math difficulty. Implications for responsiveness-to-intervention prevention models and for enhancing math problem-solving instruction are discussed.Mathematics word problems require the transfer of knowledge to novel situations, and this form of transfer can be difficult to effect (cf. Bransford & Schwartz, 1999;Mayer, Quilici, & Moreno, 1999) especially for primary-grade children (Durnin, Perrone, & MacKay, 1997; Foxman, Ruddock, McCallum, & Schagen, 1991, cited in Boaler, 1993. Whereas a calculations problem is already set up for solution, a word problem requires students to use text to determine what information is unknown and to construct and solve a number sentence for finding that unknown information. So, although calculation skill is foundational to word problems (e.g., Fuchs et al., 2006), it seems likely that for some students, word-problem skill will not develop automatically from instruction on math calculations, but rather that instruction needs to be designed specifically to prevent difficulty with word problems.The context for preventing academic difficulty in the schools has changed over the past 5 years with the introduction of multi-tiered prevention systems. 1 Adapted from the health care system,