The range of drug diversion programs in Australia has increased markedly in the last decade. The question of whether these programs really do divert offenders from the criminal justice system or simply add levels of complexity and supervision has not been adequately addressed. Using Stanley Cohen's (1985) conceptualisation of 'wider nets' (more people in system), 'denser nets' (increased intensity of intervention) and 'different nets' (new services supplementing rather than replacing existing services) we examine the potential for a range of net-widening effects in three stages of Australian court and police drug diversion processes: the recruitment of program participants, the conditions imposed as treatment and the final sentencing outcomes. Because of the potential for net-widening with diversion programs, we recommend the incorporation of net-widening impact assessments into the planning of all new diversion initiatives followed by evaluations that monitor inadvertent net-widening. Ultimately, in determining the costs and the benefits of drug diversion, net-widening may represent a threat if seen from a criminal justice perspective but a benefit from a health perspective.