Deviant partner involvement and offending risk in early adulthood Lianne J. Woodward, 1 David M. Fergusson, 2 and L. John Horwood 2 1 University of Canterbury and Christchurch School of Medicine, New Zealand; 2 Christchurch School of Medicine, New Zealand Background: This paper examines the effects of deviant and non-deviant partner involvement at age 21 on patterns of continuity and change in offending between the ages of 18 and 21 years in a birth cohort of 983 young men and women. Results: Results showed that those involved with a non-deviant partner had lower rates of offending at age 21 than those with no partner, whilst those without a partner had lower rates of offending at age 21 than those involved with a deviant partner. Associations between deviant/non-deviant partner involvement and offending risk best fitted a main effects model in which both offending at age 18 and young people’s partnership choices at age 21 made independent and additive contributions to the prediction of offending at age 21. There was no interaction between offending at age 18 and partner choice at age 21 in determining offending risk in early adulthood. In addition, the effects of deviant/non-deviant partner involvement on patterns of offending were the same for men and women, and were found to persist even after extensive control for the confounding effects of a wide range of selection factors measured during childhood and adolescence. Conclusion: These results highlight the importance of partnership choices during early adulthood in determining young people’s risk of offending as adults. Keywords: Partner relations, deviant partner involvement, antisocial behaviour, offending, longitudinal study. In the last two decades, considerable research attention has been given to the identification of risk factors associated with the development and main- tenance of antisocial behaviour problems such as conduct disorder, juvenile delinquency and offend- ing (for reviews see: Dishion, French, & Patterson, 1995; Farrington, 1998; Moffitt, 1993; Rutter, Giller, & Hagell, 1998). On the basis of this research, it is clear that substantial within-individual continuity exists in the life patterns of antisocial children, with early behaviour problems being highly predictive of later behavioural, social, and interpersonal difficul- ties during childhood and adolescence (Farrington, Lambert, & West, 1998; Fergusson, Horwood, & Lynskey, 1995; Nagin & Tremblay, 1999; Robins, 1978, 1991). However, despite the presence of robust continui- ties in antisocial behaviour over time, there is now growing evidence to suggest that not all antisocial children grow up to become severely antisocial adults. Rather, for a significant proportion of young people, discontinuity rather than continuity is the more usual life course (Farrington, 1995; Maughan & Rutter, 1998). In addition, there is also clear evi- dence to suggest that considerable across-time variability exists in overall rates of antisocial beha- viour (Cairns & Cairns, 1994; Farrington, Gallagher, Morley, St. Ledger, & West, 1986; Nagin, Farrington, & Moffitt, 1995). Specifically, rates of offending and other forms of antisocial behaviour tend to increase gradually during childhood, rise more sharply dur- ing adolescence and then begin to decline steadily as young people enter adulthood. These findings clearly suggest that behavioural development involves both continuity and change, with some young people showing highly stable patterns of antisocial beha- viour, whilst for others discontinuity is much more prominent. The demonstration of both continuity and change in antisocial behaviour over the life course has resulted in a recent upsurge of interest in the identification of individual characteristics and life experiences that encourage behavioural change (Farrington & West, 1995; Horney, Osgood, & Marshall, 1995; Laub, Nagin, & Sampson, 1998; Maughan & Rutter, 1998; Moffitt, 1993; Quinton, Pickles, Maughan, & Rutter, 1993; Sampson & Laub, 1993; Stoff, Breiling, & Maser, 1997). One factor that has been shown to play a key role in de- termining the likelihood of continuity and change in individual offending trajectories involves the forma- tion of intimate partner relationships during early adulthood (Farrington & West, 1995; Horney et al., 1995; Laub et al., 1998; Quinton et al., 1993; Sampson & Laub, 1993). In particular, despite early scepticism about the contribution of supportive partner relations to declines in offending (Gottfred- son & Hirschi, 1990), there is now increasing evi- dence to suggest that the formation of a close affectional tie with a partner may have an important influence on an individual’s risk of offending during adulthood (Farrington & West, 1995; Horney et al., 1995; Sampson & Laub, 1993). It is argued that ro- mantic partnerships are associated with increased interpersonal responsibility and commitment, which in turn act to discourage continued offending by antisocial individuals (Farrington & West, 1995; Sampson & Laub, 1990; Sampson & Laub, 1993). Viewed in this way, the formation of intimate part- nerships during early adulthood may represent a Journal of Child Psychology and Psychiatry 43:2 (2002), pp 177–190 Ó Association for Child Psychology and Psychiatry, 2002. 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