This retrospective study examined scores for 111 adult participants on the Wechsler Adult Intelligence Scale-Revised, the Wide Range Achievement Test-III and the Nelson-Denny Reading Test. All participants were referred to a university clinic for learning problems. The participants were diagnosed with a learning disability, an Attention-Deficit/Hyperactivity Disorder (ADHD) or a combination of ADHD and learning disabilities. The major results indicate significant group differences between the above three groups on two measures of reading performance from the Nelson-Denny Reading Test but only one other significant difference (Block Design) from the WAIS-R subtests. The need for administering reading performance measures to differentially diagnose between learning disabilities, ADHD and combined ADHD and learning disabilities groups in adult populations is noted. (Contains 7 tables.)