Children who are referred to mental health clinics in the preschool years pose problems for diagnosticians because of the lack of standardized instruments for assessing personality and measuring behavior of preschoolers. In response to this problem, the Children's Behavioral Classification Project has been extended into the preschool years and the Preschool Behavioral Classification Project form (PBCP) has been developed. When completed, the PBCP contained 268 behavioral items and five demographic variables (age, sex, race, socio-economic level, and clinic-nonclinic status). The PBCP was then administered to the 1350 parents. Twenty-two major factors were produced in the statistical analysis. Examples of factors produced include: sexual curiosity; disobedience; direct aggesssion; verbal hyperactivity; separation anxiety; positive social orientation; perserverance; and sociability. Presently, the test-retest reliability of the instrument is being determined. With respect to future research norms will be established for each factor for each age. Other studies which will be carried out include validity studies, reliability studies, and longitudinal studies. Eventually the focus of the research will concentrate on the use of the PBCP in evaluating the efficiency of therapeutic programs. (MLP)