Therapy process research suggests that an inverted U-shaped trajectory of client resistance, referred to as the struggle-and-working-through pattern, predicts positive treatment outcomes. However, this research may lack external validity given the exclusive focus on European Americans. This preliminary study explores differences in resistance patterns in a sample of African American and European American juvenile drug offenders and their families (n = 41) participating in Multisystemic Therapy. Resistance was coded from session recordings at the beginning, middle, and end of treatment. There were significant ethnic differences in (a) mean resistance at midtreatment, (b) resistance trajectories, and (c) predictive relationships between resistance trajectories and criminal desistance. Notably, a negative quadratic (i.e., inverted U-shaped) resistance trajectory was more characteristic of European Americans who desisted from crime, whereas a positive quadratic (U-shaped) resistance pattern was more characteristic of African Americans who desisted. There was no relationship between resistance trajectory and later drug abstinence (i.e., cannabis). Within the context of evidence-based therapies, core treatment processes may vary significantly as a function of client ethnicity. We recommend that clinical scientists make efforts to test for ethnic differences in treatment process so that therapies like Multisystemic Therapy can be understood in a more comprehensive and nuanced manner.