A large school-based sample of 9th-grade adolescents (N = 875) completed the Almost Perfect Scale-Revised (APS-R; Slaney, Mobley, Trippi, Ashby, & Johnson, 1996). Decision rules and cut-scores were developed and replicated that classify adolescents as one of two kinds of perfectionists (adaptive or maladaptive) or as nonperfectionists. A four-cluster solution further differentiating nonperfectionists was also evaluated. Criterion-related validity of the cluster solutions was supported by perfectionist and nonperfectionist group differences on select subscales of the Multidimensional Students' Life Satisfaction Scale (MSLSS; Huebner, 1994) and the Behavior Assessment System for Children, Second Edition: Self-Report-Adolescent (BASC-2: SRP-A; Reynolds & Kamphaus, 2004). Adaptive and maladaptive perfectionists were supported in both cluster solutions and validity analyses. In addition to the two types of perfectionists, the four-cluster solution differentiated two types of nonperfectionists from one that seemed similar to maladaptive perfectionists in terms of BASC-2: SRP-A scores. Although the four-cluster solution may have potential value, the three-cluster solution was recommended as more parsimonious for studies attempting to differentiate perfectionists. The findings and straightforward decision rules were generally consistent in principle with other studies attempting to classify perfectionists, although the final APS-R cut-scores differed from those of other studies of adults. The results provided additional descriptive inferences for perfectionistic and nonperfectionistic adolescents. Among other issues, the findings raised the question of whether the label of "maladaptive" for a subgroup of perfectionists was too broad given that the criterion-related validity scores revealed that the group's problems in adjustment were conspicuous only in the areas of anxiety and social stress. (Contains 2 figures, 5 tables, and 2 footnotes.)