Socioscientific issues (SSI) are complex, controversial, uncertain and value-laden issues, encompassing interdisciplinary knowledge for which there is no consensus in the scientific realm of producers of knowledge, and their teach-ing requires a change in the educational paradigm. Teachers of scientific dis-ciplines are destabilized, as the didactic formats of the SSI field differ from the pedagogical formats of their own disciplinary culture. These different teaching contexts are thus likely to put the teachers' professional identity un-der stress by subjecting them to new professional dilemmas both in their rela-tionship to the profession and in their relationship to themselves. We analyze how experienced and novice teachers negotiate these difficulties and show how experienced teachers reconcile the different strata of their professional identity (disciplinary and SSI). In particular, they assume their values as a driving force behind their commitment to teaching SSI and they have gradual-ly changed their work context to reduce the risk of teaching. We suggest that the professional development for future teachers should be based on peda-gogical guides to make them feel safe in the classroom, it should also include training in ethics to deal with professional dilemmas, as well as interdiscipli-nary and team work to bring together disciplinary professional identities.