The provision of high-quality early mathematics instruction and intervention is critical to ensure that all students are on track for academic success. Given this, identifying and utilizing assessments that can enable the detection of nonresponse to mathematics instruction is a critical aspect of early intervention. To this end, the current study explored the extent to which there were distinct patterns of performance on embedded assessments for intervention participants within the context of a large-scale randomized control trial of the ROOTS intervention. This study also examined how performance on embedded assessments was associated with pretest mathematics scores and residual gains on mathematics measures, and how those associations differed based on (a) the point in the intervention when students demonstrated difficulty, and (b) intervention intensity. Findings from this study suggest that participants fell into 4 distinct performance categories and performance classifications were associated with pretest measures and gains in mathematics achievement. Study results also highlight the potential relevance of instructional intensity and timely monitoring of student performance. Implications for intervention and instructional planning in the context of tiered instructional delivery models are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).