The cognitive attributes of Grade 1 students who responded adequately and inadequately to a Tier 2 reading intervention were evaluated. The groups included inadequate responders based on decoding and fluency criteria (n = 29), only fluency criteria (n = 75), adequate responders (n = 85), and typically achieving students (n = 69). The cognitive measures included assessments of phonological awareness, rapid letter naming, oral language skills, processing speed, vocabulary, and nonverbal problem solving. Comparisons of all four groups identified phonological awareness as the most significant contributor to group differentiation. Measures of rapid letter naming, syntactic comprehension/working memory, and vocabulary also contributed uniquely to some comparisons of adequate and inadequate responders. In a series of regression analyses designed to evaluate the contributions of responder status to cognitive skills independently of variability in reading skills, only the model for rapid letter naming achieved statistical significance, accounting for a small (1%) increment in explained variance beyond that explained by models based only on reading levels. Altogether, these results do not suggest qualitative differences among the groups, but are consistent with a continuum of severity associated with the level of reading skills across the four groups. (Contains 3 figures and 4 tables.)