The familiar register, taking an important part in daily conversations, especially in oral communications, is presented as a source of difficulties in listening as well as in speaking competencies to French Foreign Language Learners (FFLL). we aimed to meet two goals from studying this topic in the present research; the first goal is to critique of current status of the familiar register in FFL textbooks and the other is to improve the oral skills of learners, especially that of Iranian learners wishing to interact with French speakers in informal situations. In order to reach these goals, two data collection tools are used: teaching the familiar register to students of FFL at University of Tehran through five sequences and analysis of the FFL textbooks for levels B1 and B2 according to CEFR. Anchored in the sociolinguistics domain, we have applied three research methods (description, production and action) and a qualitative-quantitative methodology of data analysis. The results of this research show that the students who have participated in our sequences had not a sufficient knowledge of the French familiar register and our explicit teaching was effective based on the statistic's significant difference between the pretest and the posttest scores. They also bring to light a deficit in the teaching of the familiar register in the studied textbooks (Alter Ego 3 and 4, Le Nouvel Edito B1 and B2, Le Nouveau Taxi 3, La Saison 3 and 4).