Broadly speaking, the teaching of spoken language in Spanish schools has not been approached in a systematic way. Changes in school practices are needed in order to allow all children to become competent speakers and to understand and construct oral texts that are appropriate in different contexts and for different audiences both inside and outside school. Here we describe the construction of EVALOE ("Escala de valoración de la enseñanza de la lengua oral en contexto escolar" [Assessment scale of oral language teaching]), a flexible tool designed to assess the teaching and learning of spoken language in schools. The first part of the tool is an observation scale (for use in the classroom), and the second is a semi-structured interview carried out with the teacher after the observation. The instrument is designed to assess how teachers facilitate the development of spoken language. It also aims to further interdisciplinary collaboration with regard to the introduction of changes in teaching practices in order to promote the development of communication friendly classroom environments. A pilot test and expert review of the tool was carried out. Thirty-nine schools then participated in the field test, which involved 39 professionals (23 speech and language therapists, eight educational psychologists, and eight teachers) and two university students. Eighty observations, 34 in a preschool setting and 46 in primary schools, were carried out. The results suggest that EVALOE is a useful tool for assessing the teaching and learning of spoken language.