The topic of this third action guide was chosen because the implementation of strategic health action plans and regional health conferences increasingly requires stakeholders to define priorities. However, the definition of these priorities is preceded by a situation analysis phase. The example chosen is the situation analysis conducted to determine priorities within the framework of the health program for at-risk youth (Mutualité française and Comité français d'éducation pour la santé). The method involves identifying the observed health needs of young people, their expressed demands, and existing responses in terms of services or structures. Priorities are defined at the intersection of these three perspectives. Health needs are analyzed through a literature review; requests are gathered through interviews and surveys; and existing responses are identified within the relevant organizations and networks. The limitations of this method stem from the diversity of data sources to be utilized.