This report documents the statistical evidence concerning the validity of teacher and parent ratings on The Five P's (Parent/Professional Preschool Performance Profile). Data from 2 studies were obtained from 55 disabled children at the Variety Preschooler's Workshop during 1988-89 and from 370 disabled children at 9 schools across the country during 1986-88. Comparison of scores on The Five P's with scores on other standardized tests in the first study showed parent validity coefficients for developmental skills on the five major domains in the .54 to .72 range and teacher validity coefficients in the .48 to .74 range. The second study found that factor analysis for both teachers and parents indicates that the Developmental Skills are a different construct from the Interfering Behaviors, confirming that the Interfering Behaviors are "unique" and apart from normal developmental skills. The scales generally clustered together in the way The Five P's was theoretically organized when it was conceptualized. Tables detailing findings are appended. (Thirteen references) (Author/DB)