Cognitive-behavioral therapy (CBT) is a term that encompasses numerous specific treatment approaches for various psychiatric disorders. As the name suggests, cognitive-behavioral treatments incorporate both cognitive and behavioral strategies. With regard to depression, CBT refers to the use of both cognitive restructuring and the behavioral strategy of activity scheduling or behavioral activation.
Cognitive-behavioral approaches to the treatment of depression stem from early behavioral treatments that emerged in the 1960s and 1970s. Among the most prominent was Lewinsohn et al’s behavioral treatment for depression.  Lewinsohn proposed that depression resulted from deficient response contingent positive reinforcement, which he reported was a function of the following 3 factors: 
Individual differences in what is experienced as reinforcing
The availability in the individual’s environment of potentially reinforcing events
The skill level needed to obtain reinforcement
For example, if someone found conversing with others to be reinforcing, had other individuals available with whom to converse, and possessed the social skills needed to engage one of those individuals in conversation, then he or she could experience positive reinforcement. Lewinsohn’s treatment, therefore, aimed to increase depressed individuals’ ability to obtain response-contingent positive reinforcement and therefore improve their mood; he did this by having them identify and engage in events they described as having been, or potentially being, pleasurable and addressing skills deficits that may preclude them from obtaining the desired reinforcement from identified pleasant events. Numerous depression treatments that included activity scheduling emerged during the 1970s and 1980s. [3, 4, 1, 5, 6]
Although early versions of activity scheduling primarily focused on increasing mood-related pleasant events, Beck incorporated a form of activity scheduling into his cognitive therapy for depression, aimed at increasing both pleasant events and providing a sense of accomplishment or mastery (eg, working on a resume, completing a school assignment).  Following a component analysis of cognitive therapy that found this activity scheduling component to be as effective as the full treatment package,  interest in behavioral treatments for depression increased, leading to modern approaches called behavioral activation (BA) treatments.
Modern BA approaches are based on the same principles as early versions of activity scheduling but incorporate more sophisticated strategies for identifying activity assignments and addressing barriers to their completion. [9, 10] Several meta-analyses have examined studies of activity scheduling and BA approaches over the past several decades and have provided substantial empirical support for these approaches. [11, 12, 13]
During the 1970s, cognitive treatments for depression began to gain in popularity and empirical support, with the most well-known being Beck et al’s cognitive therapy for depression.  Cognitive therapy is based on the fundamental assumptions that (1) cognitive activity affects behavior, (2) cognitive activity can be monitored and changed, and (3) cognitive changes can lead to desired behavioral changes.  Cognitive therapy emphasizes the need to change cognitions in order to achieve improvements in mood and behavior. As mentioned above, Beck’s cognitive therapy for depression includes activity scheduling treatment strategies adapted from earlier behavioral interventions but also includes cognitive strategies such as cognitive restructuring that were designed to directly challenge and change maladaptive thoughts.
Although behavioral approaches typically do not include any direct attempts to change cognitions (but attempt to indirectly do so through changes in behavior), cognitive therapy does directly attempt to change behavior but does so for the ultimate goal of changing cognitions in order to reduce depressive symptoms. Therefore, at times, such approaches may be called either cognitive therapy or CBT, with both incorporating behavioral and cognitive interventions.
Within the CBT model, individuals with depression are viewed as exhibiting the “cognitive triad” of depression, which includes a negative view of themselves, a negative view of their environment, and a negative view of their future.  Related to the cognitive triad, depressed patients are believed to exhibit numerous cognitive distortions that maintain these negative beliefs.  Examples of these distortions include all-or-nothing thinking (ie, viewing things in black and white categories), overgeneralization (ie, assuming one negative event constitutes a pattern of never-ending negative events), and fortune telling (ie, making negative predictions about the future that are often inaccurate or negatively biased).  Within Beck’s model, negative automatic thoughts and distortions in thinking are hypothesized as stemming from problematic schemas, which are cognitive structures that influence how information is interpreted andrecalled. [17, 7] Schemasareoftentargetedinthe later phases of treatment, whereas behavioral strategies and efforts to elicit and test automatic thoughts are implemented earlier in treatment.  Elaboration of specific treatment strategies is presented below.
Because CBT for depression is a broad category that includes numerous treatment strategies, different aspects of treatment may be emphasized to a greater or lesser extent in practice. In general, however, CBT for depression includes specific behavioral strategies (ie, activity scheduling) as well as cognitive restructuring aimed at changing negative automatic thoughts.
Beck’s cognitive therapy for depression has been listed as a well-established treatment by the American Psychological Association’s Task Force on Promotion and Dissemination of Psychological Procedures since its inception in 1993. Several meta-analyses have demonstrated the effectiveness of CBT for depression. [22, 23, 24]
Individual and group-based CBT is recognized in the most recent American Psychiatric Association Guidelines for The Treatment of Major Depressive Disorder as an effective and evidence based treatment for depression.  When used, it should be integrated into the overall care that the patient is receiving (ie, communication is needed between the treating therapist and the prescribing psychiatrist or primary care physician).
The use of CBT for a particular patient is often based on patient preference, severity of depression, and ability of the patient to gain access to the treatment. The use of CBT as a stand-alone treatment is recommended for patients with mild-to-moderate major depressive disorder and should also be considered for women who are pregnant, wish to become pregnant, or are actively breast-feeding. It should also be made available for patients that express a preference to use CBT.
A combination of antidepressant medication and psychotherapy such as CBT is recommended for individuals with moderate-to-severe major depressive disorder or for teens with major depressive disorder in order to reduce the risk of relapse. [25, 26] According to the American Psychiatric Association guidelines, CBT combined with pharmacotherapy is also considered first-line treatment in patients with more severe, chronic, or complex presentations of depression. 
CBT has been used clinically in almost every imaginable patient population. No evidence-based exclusion criteria for the use of CBT for depression has been established. Many studies of CBT typically exclude individuals with specific characteristics due to beliefs that these characteristics could lead to less improvement in symptoms over the course of treatment. Typical exclusion criteria include an alcohol or other substance disorder, a psychotic disorder, organic brain syndrome, and mental retardation, with many studies also specifying that participants have major depressive disorder in the absence of suicide risk. More research on this issue is needed; many believe that individuals with these characteristics may still benefit from CBT for depression.
The support of family members and friends can assist with treatment by helping remind and encourage patients to complete important aspects of treatment such as attending therapy sessions, taking psychiatric medications (if prescribed), and completing therapy assignments. They may also be active participants in some of the activity scheduling assignments. Further, family members may be asked to attend therapy sessions in order to gain information about depression and CBT and to learn specific ways in which they can support or assist the patient.