A 20-year longitudinal study of biographical, psychological, and aptitudinal variables predictive of successful police performance is described. Subjects were 95 men appointed as deputy sheriffs in the Los Angeles County Sheriff's Department between 1947 and 1950. Among the significant predictors, stepwisediscriminant analysis yielded as "best" predictors of at least one criterion of success, age, height, the civil service written test score, scale 9 of the MMPI, the Kuder Mechanical scale, and the Guilford-Martin General Activity scale.There is need for work identifying reliable and valid predictors of police performance (for a review, see Becker & Felkenes, 1968). Although most studies have involved concurrent validity (e.g., Sterne, 1960; Baehr, Furcon, & Froemel, 1968), a 7-year prediction study by Blum (1964) found correlations between predictors (including MMPI scales) and such criteria as supervisors' ratings, misconduct and commendations. Marsh (1962), in a 10-year predictive study of sheriffs employed in Los Angeles County, established that certain performance criteria could be successfully predicted by various test scores, ratings and biodata. The present paper reports the results of a follow-up of some of these same officers after a 20-year period. The primary objectives of the study were (a) to evaluate the continued significance of Marsh's 10-year predictors as 20-year predictors and (&) to determine for each criterion the "best" among those predictors found significant. METHOD SubjectsThe subjects were 95 male law enforcement officers chosen from two randomly selected classes from the Los Angeles County Sheriff's Academy. All subjects were appointed as deputies in 1947-1950.

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has a doctorate in clinical psychology and a penchant for exploring natural areas on foot. For more than 20 years, he owned and operated an awardwinning hiking tour company on the island of Hawai'i. His published writing includes a brief section in The Call to Hawaii: A Wellness Vacation Guidebook and a number of articles in the Hamakua Times on a variety of subjects, including Hawai'i's natural and cultural history, aging well, and climate change.