This paper presents prevalence rates by race/ethnicity and age for nin
e psychiatric and substance use disorders found in a random sample of
728 male jail detainees. Two thirds of the sample detainees had had a
disorder other than antisocial personality during their lifetimes; hal
f of these had had an episode within 2 weeks of the interview. More th
an 30% currently had either a severe mental disorder or a substance us
e disorder. Detainees with severe mental disorders or substance use di
sorders were most often in jail because they had committed nonviolent
crimes. Policy implications of the results are discussed.