A decade of programmatic studies of resistance during parent training therapy is reviewed, including a brief description of a procedure developed for coding resistant behavior. Analyses of sequential interactions during treatment show that therapists' efforts to intervene produced immediate parental resistance. From baseline to midtreatment phases, there were increases in the therapists' efforts to intervene, which were in turn accompanied by Increases in parental resistance. Contextual variables such as parent pathology also correlated with higher levels of resistance. Decreases in resistance were associated with improvements in parental discipline practices. Parental resistance altered the behavior of the therapists, reducing their effectiveness. A regression analysis shows that improvements in discipline predicted fewer future arrests and out‐of‐home placem