This study is the first cross-site evaluation of the 2016 JDTC Guidelines. The goals of the evaluation were to: a) Determine the extent to which it is feasible to implement the 2016 JDTC Guidelines and the kinds of adaptation courts make to use them; b) Examine the impact on youth of the JDTC relative to TJC; c) Identify evidence for some components of the Guidelines being more or less important or not important; and d) Recommend changes to the Guidelines based on a-c. The specific research questions are: Q1. Do youth with substance use disorders (SUD) experience more positive outcomes if assigned to a JDTC rather than to a TJC? Q2. Are different interpretations of the Guidelines by the courts associated with better outcomes? Q3. Are there certain Guidelines that, if present, are associated with better outcomes? Q4. Are there Guidelines that, if absent, do not seem to be associated with worse outcomes (i.e., they are not necessary)? Q5. Do some of the seven broad objectives have a stronger association with outcomes than others? Q6. Is there counterfactual evidence that instances of NOT following the Guidelines produces worse outcomes?