‘There is probably no area of behaviour or psychiatric disorder riper for an experimental design than conduct problems’. Lee Robins (Robins, 1992, p. 11) based this opinion on the following arguments: (1) the population at risk is known, (2) we have the appropriate instruments to measure the presence of the problem, (3) there is a large window of opportunity (from age 10 to 16) to evaluate their occurrence and (4) a number of hypothetical causal agents have been identified which are good candidates for prevention: disorganized neighbourhoods, family adversity, poor parenting, cognitive and emotional deficits. Many other calls have been made for preventive trials over several decades, because corrective interventions have not been shown to be generally successful, and because preventive experiments appear the best means of testing hypothetical causes of conduct disorder (Bovet, 1951; Cabot, 1940; Earls, 1986; Farrington et al., 1986; Lipton et al., 1975; McCord, 1978; Tonry et al., 1991).

The aims of this chapter were to identify well designed preventive trials, assess their effectiveness and give examples of successful and unsuccessful interventions in the prevention of conduct problems in children. We expected that a significant research effort had been put forward to implement preventive interventions, since the hypothetical causal agents and the developmental course of conduct disorder have been identified and re-identified over more than a century (Andry, 1960; Carpenter, 1851; Glueck & Glueck, 1934; Hart, 1910; Jenkins & Glickman, 1947; Pitkanen, 1969; Quetelet, 1833; Robins, 1966; Rutter et al., 1981; Shaw & McKay, 1942).