This, the first part of a two-part paper, focuses on the importance of the voices of teachers in educational research, as they are key stakeholders in any educational endeavor and among the main agents of educational change.Therefore, even in the most learner-centered of approaches to teaching, it is essential to gather data from teachers.However, in examining the educational research from the 1990s to the present day, the focus appears to have shifted from teachers' voices to students' voices, which leaves an essential part of the picture missing.To address this absence, data was collected from language teachers on a new MA program jointly offered by a Colombian university and one in the United States, which is described in the second portion of the present article.The third portion of the present article introduces and explores the notion of 'messy data', and the final portion looks at the research on CLIL in Latin America in relation to teachers ' voices.