The development, norming, and validation of the Preschool Behavior Questionnaire (PBQ) are described. The questionnaire was developed to be a screening instrument for use by mental health professionals for the early detection of children's behavior problems. The scale was standardized on a group of preschoolers aged three to six, including male and female and black and white children. The PBQ is a modification of an English checklist with additional questions from a variety of sources. Significant differences were found between mean scores for 496 children from preschools for the general public and 102 preschoolers in programs specifically for emotionally disturbed children. A factor analysis of the 36 items yielded a three factor solution. The factors were labeled: (1) Hostile-Aggressive; (2) Anxious-Fearful; and (3) Hyperactive-Distractable. After analysis the questionnaire was shortened to 30 items. Males scored higher than females and blacks scored higher than whites. Administration and scoring are described and norms are given. It is recommended that any child scoring above the 90th percentile on the total or on any of the three subscores should be considered for further examination. (Author/CTM)