Recently, there have been quite a number of Acceptance Commitment Therapy meta-studies. This new one, published in the Journal of Affective Disorders and linked below, argues that we don’t need any more RCTs on seeing whether ACT helps vis a vis nothing or an inert condition.
In other words, ACT works for depression and anxiety, when compared to ‘treatment as usual.’ However, more understanding is needed when comparing ACT to other evidence-based practices such as CBT.
Link: http://www.jad-journal.com/article/S0165-0327(15)30365-7/abstract