Results are compared in studies of 4 male cohorts - 1 all white, 1 all black, and 2 racially representative of the population - growing up in different eras, followed past varying portions of their adult lives, living in different parts of the US. Despite sample differences and differences in sources of information and in the variables used to measure both childhood predictors and adult outcomes, some striking replications appear with respect to childhood predictors of adult antisocial behaviour. All types of antisocial behaviour in childhood predict a high level of antisocial behaviour in adulthood and each kind of adult antisocial behaviour is predicted by the number of childhood antisocial behaviours, indicating that adult and childhood antisocial behaviour both form syndromes and that these syndromes are closely interconnected. Also confirmed across studies are: (1) adult antisocial behaviour virtually requires childhood antisocial behaviour; (2) most antisocial children do not become antisocial adults; (3) the variety of antisocial behaviour in childhood is a better predictor of adult antisocial behaviour than is any particular behaviour; (4) adult antisocial behaviour is better predicted by childhood behaviour than by family background or social class of rearing; (5) social class makes little contribution to the prediction of serious adult antisocial behaviour.