Four-year old children in the New York State Experimental Prekindergarten Program (PreK) were administered three cognitive and two behavioral measures to determine if the data would provide sets of a smaller number of variables, to see if the variables overlapped, and to determine the appropriateness or redunduncy of the tests. The tests were: the (1) Walker Readiness Test for Disadvantaged Preschool Children; (2) Cooperative Preschool Inventory; (3) Peabody Picture Vocabulary Test; (4) California Preschool Social Competency Scale; and (5) Schaeffer's Classroom Behavior Inventory. Factor analysis incorporated nine socioeconomic background variables, two duration/attendance variables, 18 cognitive variables, and eight behavioral variables. These variables were reduced to parent education; family income and size; length of residence; factual and conceptual knowledge; perceptual discrimination; social adjustment or constructive participation; extraversion/introversion; hours present and prior PreK experience; and elapsed time between pretest and posttest. Results indicated that the ordering of large numbers of variables into smaller numbers of interpretable factors affords more insight into the structure of a data set. The Peabody Picture Vocabulary Test and the Cooperative Preschool Inventory contained the same general cognitive/verbal dimension. Analysis of the Classroom Behavior Inventory indicated that the instrument has high stability and three components in common with the California Preschool Social Competency Scale. (JAC)