Purpose: This article provides benchmark data on within-group effect sizes from published randomized clinical trials supporting the efficacy of dialectical behavioral therapy (DBT) for borderline personality disorder (BPD) in adults aged 18-65 years. Method: Within-group effect sizes were calculated via the Glass approach and adjusted for sample size using Hedges's g then aggregated to produce benchmarks for symptoms commonly associated with BPD, such as self-harm, depression, and anger. Results: Aggregate within-group effect sizes are presented separately for treatment (DBT) and control (treatment as usual) groups and for interviewer assessed and self-reported outcome measures. Discussion: Community-based practitioners can use these benchmarks as a comparison tool to evaluate the ways in which they are adopting or adapting the DBT intervention and to determine if the intervention should be modified or replaced, given their unique practice setting and client population.