Although research suggests that certain cognitive functions predict the likelihood of intervention response for students who receive Tier 2 instruction through a response to intervention framework, researchers know less about cognitive predictors of response to Tier 3 instruction. This study measured 2nd and 3rd graders' performance on 7 cognitive tasks associated with reading outcomes. Participants then received 10 weeks of targeted intervention with the HELPS One-on-One Reading Fluency Program. Repeated measures multivariate analyses of variance using both norm-referenced and growth score criteria failed to demonstrate significant differences between the cognitive processing profiles of students who met response criteria and those who did not. Only phonological awareness indicated an area of significant processing deficit. Findings did not support a continuum of severity hypothesis and instead provided support for the heterogeneity of reading disorders. [For a related report, see ED571936.]