Cluster analysis was applied to 12 measures of intellectual, personality, self-related, and social functioning collected in the 1st cross-sectional wave of the Berlin Aging Study (BASE; N = 516). Central questions concerned the number, profile desirability (functional status), and membership of the subgroups obtained. Of the 9 subgroups extracted, 4 reflected different patterns of desirable functioning (47% of the sample), and 5 reflected less desirable functioning (53%). Relative risk of a less desirable profile was 2.5 times higher for the oldest old (85-103 years) than for people between the ages of 70-84 years and was 1.25 times higher for women compared with men. Relationships with education, health, and mortality suggested underlying systemic differences. Consistent with theoretical propositions about a “4th age” and the incomplete architecture of life span development (P. B. Baltes, 1997), the oldest old appear to have a distinct and less desirable psychological profile. (PsycINFO Database Record (c) 2007 APA, all rights reserved) (from the journal abstract)