The Longitudinal Interval Follow-up Evaluation (LIFE) will provide a comprehensive cross-sectional and longitudinal picture of the symptomatic and psychosocial course and outcome of all participants in this study. Scores range from 0-3 on certain disorders and 0-6 for other disorders. High scores indicate high level of symptom impairment.

Parent and adolescent reported depressive and manic symptoms will be measured via the Child Mania Rating Scale (CMRS). The CMRS is a valid 21-item screening instrument, reflecting the DSM-IV criteria for a manic episode, with each response rated on a four-point Likert-type scale with scores ranging from 0 to 3. High scores indicate higher level of symptoms.

Parent and adolescent reported depressive and manic symptoms will be measured via the Child Mania Rating Scale (CMRS). The CMRS is a valid 21-item screening instrument, reflecting the DSM-IV criteria for a manic episode, with each response rated on a four-point Likert-type scale with scores ranging from 0 to 3. High scores indicate higher level of symptoms.

Parent and adolescent reported depressive and manic symptoms will be measured via the Child Mania Rating Scale (CMRS). The CMRS is a valid 21-item screening instrument, reflecting the DSM-IV criteria for a manic episode, with each response rated on a four-point Likert-type scale with scores ranging from 0 to 3. High scores indicate higher level of symptoms.

Parent and adolescent reported depressive and manic symptoms will be measured via the Child Mania Rating Scale (CMRS). The CMRS is a valid 21-item screening instrument, reflecting the DSM-IV criteria for a manic episode, with each response rated on a four-point Likert-type scale with scores ranging from 0 to 3. High scores indicate higher level of symptoms.

We will assess suicidal events (past and over follow-up) with the Pediatric Version of the Columbia-Suicide Severity Rating Scale (C-SSRS). The C-SSRS has sound psychometric properties, yields ratings of widely accepted definitions of youth suicidal events, and was used in other pediatric treatment trials yielding standardized outcomes to compare across studies. This is a semi-structured interview that includes yes/no questions as well as narrative. It captures number of suicidal events as well as type and severity.

We will assess suicidal events (past and over follow-up) with the Pediatric Version of the Columbia-Suicide Severity Rating Scale (C-SSRS). The C-SSRS has sound psychometric properties, yields ratings of widely accepted definitions of youth suicidal events, and was used in other pediatric treatment trials yielding standardized outcomes to compare across studies. This is a semi-structured interview that includes yes/no questions as well as narrative. It captures number of suicidal events as well as type and severity.

Self-reported depressive and manic symptoms will be measured via the Mood and Feelings Questionnaire (MFQ). Responses are made on a 3-point scale ("0=not true", "1=sometimes true" and "2=true").

Self-reported depressive and manic symptoms will be measured via the Mood and Feelings Questionnaire (MFQ). Responses are made on a 3-point scale ("0=not true", "1=sometimes true" and "2=true").

Self-reported depressive and manic symptoms will be measured via the Mood and Feelings Questionnaire (MFQ). Responses are made on a 3-point scale ("0=not true", "1=sometimes true" and "2=true").

Self-reported depressive and manic symptoms will be measured via the Mood and Feelings Questionnaire (MFQ). Responses are made on a 3-point scale ("0=not true", "1=sometimes true" and "2=true").

Adolescents will also complete the self-report Suicidal Ideation (SIQ), which is intended to identify adolescents whose level of suicidal ideation is severe enough to warrant further intervention. Each item is rated on a 7-point Likert-type scale (0= "I never had this thought" to 6="almost every day") and is used to indicate the frequency with which the adolescent experiences each thought.

Adolescents will also complete the self-report Suicidal Ideation (SIQ), which is intended to identify adolescents whose level of suicidal ideation is severe enough to warrant further intervention. Each item is rated on a 7-point Likert-type scale (0= "I never had this thought" to 6="almost every day") and is used to indicate the frequency with which the adolescent experiences each thought.

Adolescents will also complete the self-report Suicidal Ideation (SIQ), which is intended to identify adolescents whose level of suicidal ideation is severe enough to warrant further intervention. Each item is rated on a 7-point Likert-type scale (0= "I never had this thought" to 6="almost every day") and is used to indicate the frequency with which the adolescent experiences each thought.

Adolescents will also complete the self-report Suicidal Ideation (SIQ), which is intended to identify adolescents whose level of suicidal ideation is severe enough to warrant further intervention. Each item is rated on a 7-point Likert-type scale (0= "I never had this thought" to 6="almost every day") and is used to indicate the frequency with which the adolescent experiences each thought.

Adolescents will also complete the Difficulties in Emotion Regulation (DERS), a 36-item questionnaire assessing emotional dysregulation. Participants indicate how often each item applies to them on a scale from 1="almost never; 0-10 percent" to 5= "almost always; 91-100 percent".

Adolescents will also complete the Difficulties in Emotion Regulation (DERS), a 36-item questionnaire assessing emotional dysregulation. Participants indicate how often each item applies to them on a scale from 1="almost never; 0-10 percent" to 5= "almost always; 91-100 percent".

Adolescents will also complete the Difficulties in Emotion Regulation (DERS), a 36-item questionnaire assessing emotional dysregulation. Participants indicate how often each item applies to them on a scale from 1="almost never; 0-10 percent" to 5= "almost always; 91-100 percent".

Adolescents will also complete the Difficulties in Emotion Regulation (DERS), a 36-item questionnaire assessing emotional dysregulation. Participants indicate how often each item applies to them on a scale from 1="almost never; 0-10 percent" to 5= "almost always; 91-100 percent".

Following the year-long DBT intervention, patients and parents will complete an 18-item Treatment Satisfaction Questionnaire. This assesses clients' satisfaction of the service (responses range from quite dissatisfied to very satisfied) as well as whether or not the service addressed the clients' needs.

Following the year-long DBT intervention, patients and parents will complete an 18-item Treatment Satisfaction Questionnaire. This assesses clients' satisfaction of the service (responses range from quite dissatisfied to very satisfied) as well as whether or not the service addressed the clients' needs.

Following the year-long DBT intervention, patients and parents will complete an 18-item Treatment Satisfaction Questionnaire. This assesses clients' satisfaction of the service (responses range from quite dissatisfied to very satisfied) as well as whether or not the service addressed the clients' needs.

Following the year-long DBT intervention, patients and parents will complete an 18-item Treatment Satisfaction Questionnaire. This assesses clients' satisfaction of the service (responses range from quite dissatisfied to very satisfied) as well as whether or not the service addressed the clients' needs.

Borderline and antisocial personality symptoms will be assessed using the Structured Interview for DSM-IV Personality. The SID-P uses a semi structured interview format to assess for symptoms of personality disorders. Scores one each item range from 0 to 3 and high scores indicate symptoms of borderline personality disorder and levels of impairment.

Borderline and antisocial personality symptoms will be assessed using the Structured Interview for DSM-IV Personality. The SID-P uses a semi structured interview format to assess for symptoms of personality disorders. Scores one each item range from 0 to 3 and high scores indicate symptoms of borderline personality disorder and levels of impairment.

The Children's Affective Lability Scale (CALS) is a reliable 20-item adolescent- and parent-reported measure of mood lability, derived from the adult Affective Lability Scale that was specifically designed for adults with BD. It yields a total score as well as an angry/depressed factor and a disinhibited/impersistent factor.

The Children's Affective Lability Scale (CALS) is a reliable 20-item adolescent- and parent-reported measure of mood lability, derived from the adult Affective Lability Scale that was specifically designed for adults with BD. It yields a total score as well as an angry/depressed factor and a disinhibited/impersistent factor. Item scores range from 0 to 4 and higher scores indicate higher affective lability.

The Children's Affective Lability Scale (CALS) is a reliable 20-item adolescent- and parent-reported measure of mood lability, derived from the adult Affective Lability Scale that was specifically designed for adults with BD. It yields a total score as well as an angry/depressed factor and a disinhibited/impersistent factor. Item scores range from 0 to 4 and higher scores indicate higher affective lability.

The Children's Affective Lability Scale (CALS) is a reliable 20-item adolescent- and parent-reported measure of mood lability, derived from the adult Affective Lability Scale that was specifically designed for adults with BD. It yields a total score as well as an angry/depressed factor and a disinhibited/impersistent factor. Item scores range from 0 to 4 and higher scores indicate higher affective lability.

The Dialectical Behavior Therapy Barriers to Implementation (DBT-BTI) is a 26-item self-report survey that assesses barriers to DBT implementation in four domains: team, direction/motivation, theoretical position/philosophy, and administrative/structural problems. It is a yes/no questionnaire and higher scores indicate higher challenges in implementation. To be completed by DBT therapist participants.

The Dialectical Behavior Therapy Barriers to Implementation (DBT-BTI) is a 26-item self-report survey that assesses barriers to DBT implementation in four domains: team, direction/motivation, theoretical position/philosophy, and administrative/structural problems. It is a yes/no questionnaire and higher scores indicate higher challenges in implementation. To be completed by DBT therapist participants.

Therapists will complete this well-validated and widely used measure, and is the only measure available that is designed to assess barriers and facilitators at each of the levels proposed within one instrument.

Therapists will complete the Barriers and Facilitators Assessment Instrument which is a well-validated and widely used measure, and is the only measure available that is designed to assess barriers and facilitators at each of the levels proposed within one instrument. It is a 16 item Likert scale questionnaire ranging from 1 to 6 with some items being reverse scored. High scores generally indicate challenges to implementation.

The Implementation Climate Scale will enable the team to document relevant organizational processes the aid in implementation of this treatment and provide a context for other evidence-based treatment dissemination studies. This is a Likert scale from 0 to 4 with low scores indicating challenges with implementation.

The Implementation Climate Scale will enable the team to document relevant organizational processes the aid in implementation of this treatment and provide a context for other evidence-based treatment dissemination studies. This is a Likert scale from 0 to 4 with low scores indicating challenges with implementation.

The Dialectical Behavior Therapy (DBT) Therapist Self-Assessment will allow for DBT therapists to provide subjective appraisals of their own level of comfort and confidence in applying the treatment. It also assesses the need for additional supervision from the study supervisor, consultant, and/or peer. Scores range from 1 to 7 on a Likert scale and high scores indicate high therapist level of comfort in implementing the treatment.

The DBT Therapy Tracking Form will be used to document the date of the therapy session, type of session, session duration, content, and scheduled date for next therapy visit. This form will be completed by the DBT study therapist after each therapy session.

The DBT Therapy Tracking Form will be used to document the date of the therapy session, type of session, session duration, content, and scheduled date for next therapy visit. This form will be completed by the DBT study therapist after each therapy session.

The DBT Therapy Tracking Form will be used to document the date of the therapy session, type of session, session duration, content, and scheduled date for next therapy visit. This form will be completed by the DBT study therapist after each therapy session.

Participants and study therapists will be asked to complete the Dialectical Behavior Therapy Continuation Questionnaire to assess reasons for continuing or not continuing to proceed with the DBT treatment. Items are rated from 1 (strongly disagree) to 7 (strongly agree)

The Therapist Supervision Hours Log will be completed by the DBT study therapist for all supervision received on study cases. This form includes date of supervision, duration of supervision, and type of supervision.