The current study examines the discriminate validity of measures of four different components of attention between analogue ADHD college student subjects and control subjects in an attempt to determine which aspects of attentional processes are impaired in ADHD. The components of attention assessed were derived from two neuropsychological models of attention proposed by Allen Mirsky (citation) and Russell Barkley (citation), and include: Focused Attention, Sustained Attention, Response Inhibition and Encoding. Because clients with ADHD have often been seen as having difficulty in all of these areas, it was hypothesized that they would perform more poorly than the controls on all of the assessment measures. Logistic regression equations were used for each of the factors to determine how well they predicted group membership. Only the equations including the measures of focused and sustained attention were statistically significant, correctly classifying 67% and 66% of the subjects, respectively. An equation including measures of all four types of attention correctly classified 82% of the subjects. Subjects were administered the Brief Symptom Inventory as part of the test battery and subjects in the ADHD group scored significantly higher on all subscales. Thus, the GSI score was added to the combined factor equation. The resulting equation perfectly predicted group membership. The results are discussed in terms of the current literature on ADHD as well as their implications for clinical assessment. Limitations of the study and future directions are also discussed.