Studies have found that in order for a prevention program to be effective, it needs to be delivered over a long period of time to continually reinforce skills.

Supporting Citations:

Ellickson, P.L., Bell, R.M. and McGuigan, K. (1993). Preventing adolescent drug use: Long-term results of a junior high program. American Journal of Public Health, 8, 856-861.

Flay, B.R. et al. (1989). Six year follow up of the first Waterloo smoking prevention trial. American Journal of Public Health 79(10), 1371-1376.

Gottfredson, D.C. (1997). School-based crime prevention. In L. Sherman (Ed.), Preventing crime: what works, what doesn't, what's promising: A report to the United States Congress (pp. 5-1 - 5-74). Washington, DC: US Department of Justice.