Professionals do not only, as is today widely agreed on, work to construct institutionally workable identities for their clients in interaction, they also have to carry out substantial identity work themselves. Such work can be considerably more complicated in interactions which have a triadic structure, i.e. in which professionals from two different institutions and clients interact, demanding of professionals to invoke situational identities which match their relationships towards each other as well as towards the clients. By discussing the identity work of two professionals in a care planning conference, this article traces the difficulties that such a structure presents to practitioners. In addition, it sets out to show how ethnomethodologically informed membership categorization analysis and positioning analysis, as it was developed by discursive psychology, can be combined in the analysis of social work interactions in order to shed light on the identity work of social work professionals.