This study sought to investigate the coherence of changes observed in diagnostic criteria for borderline, schizotypal, obsessive-compulsive, and avoidant personality disorders. Five hundred, forty-nine patients were independently evaluated 2 years apart, and correlations of observed changes in each diagnostic criterion with changes in other criteria were examined to determine if there was within-syndrome consistency in these changes. The observed changes in criteria were consistent within syndrome (median alpha = 0.72 across 4 disorders), and reasonably specific to that syndrome relative to the other disorders. The results support the validity of these criterion sets as representing coherent syndromes.