The identification of suitable topics in action research can be challenging due to the complex nature of the educational context and the diverse factors that influence problem identification processes. This qualitative multi-case study explores problem identification among pre-service teachers involved in action research (AR). Twenty-nine participants (pre-service teachers, university-based supervisors, and school mentors) from two South American (Colombia and Chile) initial Foreign Language Teacher Education programs were interviewed on problem identification origins and influential factors. The study also used document analysis of program curricula, course programs, syllabi, and standards for the foreign language teaching profession across contexts. Thematic analysis suggests that problem identification has both bottom-up and top-down sources, and it is influenced by the prescriptive and facilitative roles of mentors and supervisors, the pre-service teachers' research competences, and a series of contextual factors. We discuss the results along with integrated data, point out several critical issues for action research in initial L2 teacher education and introduce a set of considerations to facilitate processes of problem identification.