Here is a useful review of studies regarding the effectiveness of solution-focused therapy.
A total of 43 studies were included in the review, of which 26 were randomised. Participants in the studies were counted as individuals or as families, depending on the study. The total participants per study ranged from six children to over 300 adults.
The author’s conclude:
There was strong evidence that solution-focused brief therapy was an effective treatment, for a wide variety of behavioural and psychological outcomes. It seemed to be shorter, making it cheaper than alternative treatments.
However, there is some commentary to suggest that the authors may have been ‘overly generous.’