Developing solution strategies, effortful procedures that students employ to solve a specific problem, is an important mathematical goal. Studies have documented intraindividual strategy variability and its significance for learning, but only some have addressed the interindividual strategic diversity across students within a classroom. This study analyzed classroom strategy diversity using assessments of 527 kindergartens to 2nd-grade students. Latent growth modeling analysis revealed that the best fit was a spline model featuring two phases of linear growth with different growth rates (i.e., one in Kindergarten, the other from Kindergarten spring to second grade). A growth mixture modeling analysis demonstrated that only one latent class existed within the data, which supports the homogeneity of the identified growth trajectory among students. We also analyzed the relations of their learning to the interindividual strategy diversity in their classrooms via a multilevel latent growth model. The results showed that early encouragement of student-generated strategies and later guidance toward research-based effective strategies most supported mathematical growth. This finding aligned with the previous work regarding classroom strategic diversity. Educational relevance and implications statementDeveloping solution strategies is an important mathematical goal. Do children benefit from being in classrooms using diverse strategies or a smaller range of efficient strategies? Does this depend on children's phase of learning? We found that early encouragement of student-generated strategies followed by later guidance toward research-based effective strategies most supported mathematical growth.