The amount of information that students successfully learn and later recall from each intervention session is limited and is called the acquisition rate (AR). Research has consistently supported the effects of modifying intervention set sizes with AR data, but research with AR is in its infancy. The current study compared the relationship between AR while learning words with working memory, short-term memory, and reading skills. Participants were 52 fourth- and fifth-grade students with and without learning disabilities (LDs). Working memory (r = 0.34), short-term memory (r = 0.41), and word reading skills (r = 0.57) all moderately correlated with AR, but word reading skills accounted for 32% of the variance and the other two scores added little unique variance. The corrected correlation coefficients were higher for the word reading with AR than with any other variable and were essentially equal for both groups (r = 0.73 for average readers and r = 0.75 for students with an LD in reading). Thus, the data not only support the validity of making decisions with AR data but also suggest that AR is more consistent with a skill-by-treatment interaction framework than an aptitude-by-treatment interaction approach. Potential applications, directions for future research, and limitations are discussed.