This is an extension study related to an ongoing implementation study of dialectical behavior therapy (DBT) for adolescents with bipolar disorder, in collaboration with investigators at the University of Pittsburgh. During the conduct of that initial study (the DITO study; REB PIN 042-2018), compelling questions have been raised by the investigators, study therapists, and participants/patients about what will happen following participation in the initial study: Which DBT outcomes are sustained over time? Will patients request and/or require additional booster sessions? Will study therapists remain adherent to the treatment model? There is sparse knowledge regarding what happens after a course of DBT is completed, and this study seeks to advance our understanding of what happens in the year after DBT by addressing these questions. This study provides a unique opportunity to examine the frequency, dose, and indications for ongoing DBT treatment for participants who have completed one year of DBT at the Centre for Youth Bipolar Disorder (CYBD). In the spirit of the original dissemination and implementation study, this study is focused on "real-world" issues routinely faced by study therapists and patients, and anticipated findings will inform future randomized controlled trials on this topic.