Background: 'Learning to Learn' (L2L) is considered a key skill for the twenty-first century. It is understood here as a hyper-competence, which mobilises resources of the individual and/or groups in a sense-making effort to improve or update one's own learning. By means of classroom assessment during the teaching-learning cycle, teachers can promote this competence in their daily practice. This paper focuses on the L2L-assessment relationship, presenting data from an international qualitative research project conducted in Brazil, Ecuador, Italy, Mexico, Spain and Uruguay from a comparative perspective. Purpose: The study sought to explore the relationship between teachers' L2L conceptualisations and their assessments in a sample of preschool, primary and secondary school teachers. Key questions addressed were: how did interviewed teachers define L2L? What, if any, was the connection between teachers' assessment methods and their own L2L definition? Methods: The analysis drew on data collected from 123 interviews with teachers, deploying a qualitative descriptive approach. L2L definitions were classified as broad or narrow according to Hounsell. A connection was assigned to each interview depending on whether teachers' assessment and L2L responses included aspects related to L2L theory. Findings and conclusion: Around one-third of interviewees provided a definition of L2L consistent with the intended purposes of assessments that contribute to the development of L2L. Approximately one-fifth was classified with partial connection and almost half was classified as showing no connection. The L2L-assessment relationship is explored in terms of similarities and differences between countries. Overall, the study draws attention to the need for increasing teacher awareness of the L2L-assessment connection during initial and inservice teacher education, in order for teachers to develop assessment practices conducive to L2L.