The question of whether attention-deficit/hyperactivity disorder (ADHD) represents a continuum of attentional and executive dysfunction or a natural category has yet to be extensively investigated. Subjective report and neuropsychological data from 437 individuals referred for neuropsychological evaluation were analyzed using latent class and taxometric analyses (mean above minus below a cut [MAMBAC], maximum eigenvalue [MAXEIG], and latent mode [LMODE]). Results indicated no significant

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... e for a taxonic representation of ADHD across multiple procedures and indicator sets. Similarly, there was no evidence that ADHD subtypes represent a qualitative distinction. These findings may suggest that current diagnostic conceptualizations are inadequate for accurately identifying and characterizing individuals with problems related to attention and executive dysfunction. Alternatively, the null findings may have resulted from inadequate indicator selection. A dimensional model may better facilitate accurate identification of individuals at risk for functional impairment.