The objective of the current study was to test the real world effectiveness of Dialectical Behaviour Therapy (DBT) for the treatment of Borderline Personality Disorder (BPD) in a community mental health clinic. Clients diagnosed with BPD and who were in various stages of DBT were recruited for a cross-sectional study. The current study assessed core BPD symptoms and skill deficits that are targeted by DBT and compared these indices across clients in pre-DBT treatment, in active DBT skills group and with those who graduated from DBT to determine whether meaningful improvements occur with DBT. Results revealed a decrease in general BPD symptoms from the pretreatment group to the graduate group including lower levels of cognitive, emotional, behavioural, and interpersonal dysfunction. The higher functioning of the graduate group relative to those in the pretreatment stage suggests a positive effect of this particular version of DBT as a means of improving core areas of functioning in clients with BPD in the context of a community-based setting. Limitations of the current study and future research are discussed.