Using longitudinal data from the first 6 waves of the Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K), the authors examined mathematics achievement and growth trajectories by learning disability (LD) subgroups. The 2-level (time-student) growth curve model showed that lower levels of mathematics achievement were already evident at kindergarten entry for all subgroups of students identified as LD during the elementary school years. Results indicate that students with LD as a group made smaller gains in mathematics than students without disabilities. This finding underscores the need for early identification combined with frequent assessment of progress and responsive instruction. (Contains 3 tables and 1 figure.)