The purpose of this study is to compare two psychological treatments for major depressive disorder (MDD): cognitive-behavioral therapy (CBT) and CBT-Skill Enhanced (CBT-SE). CBT is well-studied, research-supported treatment for depression. CBT-SE is a variant of CBT that places greater focus on helping clients to developing the skills of CBT.

The study will enroll 150 participants with MDD. Participants will be randomized to CBT or CBT-SE, with 75 participants being assigned to each condition. For both conditions, treatment will be provided over 12 weeks, with a 6 month follow-up period.

Potential participants are asked to complete an initial screening and an intake evaluation to determine eligibility. After entering the study, participants are asked to complete evaluations at 4 weeks and at 12 weeks. They are also asked to respond to self-report instruments before and after each session. Following the 12 week treatment, participants are asked to complete monthly follow-up surveys for 6 months.

The primary objectives of this study are three-fold. The first is to compare the outcomes of the two treatments. The second is to evaluate potential mediators of any treatment differences. The third is to evaluate the process of change in these two versions of CBT.

Inclusion Criteria:

1. diagnosis of major depressive disorder (MDD) according to DSM-5 criteria;
2. 18 years old or older;
3. residence in the state of Ohio;
4. access to a reliable internet connection (to participate in virtual sessions); and
5. being able and willing to give informed consent.

Exclusion Criteria:

1. current or past diagnosis of bipolar disorder or a psychotic disorder;
2. moderate or severe substance use in the past 6 months (where "moderate" is defined as 4-5 symptoms and "severe" is defined as 6 + symptoms of those listed in DSM-5 for each of the substance-related disorders);
3. current disorder other than MDD if it constitutes the predominant aspect of the clinical presentation and if it requires treatment other than that being offered;
4. currently participating in a treatment for an emotional disorder, including any individual psychotherapy or psychiatric medications used to treat a mood or anxiety disorders;
5. clear indication of secondary gain (e.g., court-ordered treatment); and
6. current suicide risk or significant intentional self-harm in the last six months sufficient to preclude treatment on an outpatient basis.

We will consider requests for data sharing, pending approval from our IRB.