As many as you are competent in.
We recommend that you order your specialities by degree of expertise. For example, if you work mainly with addiction, then ‘addiction' should be selected first. By default, all sub-specialities are ticked, but you can remove any that don't apply. So if you work with shopping addiction but not gambling, you can de-select the latter.
Click here to view a video showing how to remove sub-specialities and re-order the specialities.