International audience This exploratory study aims to measure and understand the nature of the impact of proactive in-class tutoring group sessions on the development of first-year Social Sciences students'English skills. Ten tutorials based on a corpus of texts studied in lectures were offered to them between a pretest and a posttest. Even though the results should be interpreted with great care, this paper shows that the students who attended these tutoring sessions obtain better grades and progress significantly over the course of the term in comparison to those who did not participate in the mentorship program. These findings are even more preeminent if attendance to this program is associated with lecture attendance, be the students volunteers or required to attend these tutoring sessions. Qualitative analysis of students' responses showed that they were as sensitive to their tutor's friendliness and benevolence (social congruence) as to his ability to respond to their social cognitive needs and his capacity to adapt and bring specific knowledge into general use (cognitive congruence).