This is the protocol for a review and there is no abstract. The objectives are as follows: To examine the effectiveness and acceptability of all third wave CBT approaches compared with all other psychological therapy approaches for acute depression.To examine the effectiveness and acceptability of different third wave CBT approaches (ACT,compassionate mind training, functional analytic psychotherapy, extended behavioural activation and meta-cognitive therapy) compared with all other psychological therapy approaches for acute depression.To examine the effectiveness and acceptability of all third wave CBT approaches compared with different psychological therapy approaches (psychodynamic, behavioural, humanistic, integrative, cognitive-behavioural) for acute depression.