Juvenile drug treatment courts (JDTCs) continue to be popular. However, results of a recent meta-analysis raised doubts regarding their effectiveness over traditional juvenile justice system processing. The objective of this study was to systematically review the qualitative and quantitative evidence related to the inner workings of JDTCs to identify ways to improve outcomes. We conducted an extensive systematic search for process and implementation studies, resulting in 59 studies that met eligibility criteria. We used meta-aggregation methods to extract 477 study findings and categorized the findings thematically. We report on a subset of findings within four thematic categories containing the largest number of methodologically credible findings: (1) family members as stakeholders in the JDTC process, (2) standards for ensuring accountability and youth compliance with court expectations, such as the consistent application of behavioral contingencies, (3) the availability of community and school services, and (4) the various needs of JDTC clients, such as mental health treatment. Based on these findings, we suggest a modified causal change model for JDTCs that extends the theoretical framework for JDTCs to incorporate improving youth psychosocial functioning as an important outcome. Implications for the role of JDTCs within the juvenile justice system are discussed.