Again, for treatment to be successful, continuity of care is essential. Research has shown that outcomes are more favorable when treatment is begun during incarceration and continues in the community following re-entry. For example, here we see that 3 years post-treatment, those who received prison-based treatment followed by community-based treatment were more likely to be drug- and arrest-free 3 years after release compared to those who did not participate in treatment or who participated only in prison-based treatment.