ABSTRACT  The purpose of this study was to identify the professional actions of early French immersion teachers in the classroom and to ascertain teachers' judgment regarding the effectiveness of these actions. Critical Incident Technique was used to gather professional actions from teachers and their school principals. The majority of professional actions identified by the immersion teachers referred to the management of vocabulary instruction through the use of systematic instructional strategies across the school curriculum. One of the implications drawn was the need for a distinct teacher preparation program for teaching in a second language context. Sheltered programs for the preparation of preservice teachers in all areas of the school curriculum were suggested to upgrade their linguistic abilities in the various subject areas.