Factors which influence the acquisition of a second language within the framework of the British educational system are examined in this study. An ongoing, 10-year, language experiment (1964-74) involving 18,000 students ranging in age from 8 to 13, concentrates on determining the desirability and practicability of starting modern language programs in the elementary schools of England. Principal objectives of the experiment examined in this report include: (1) evaluation of the effect of the introduction of French at the primary level on achievement in other areas of the curriculum, (2) assessment over a period of years of the level of achievement in French of the pupils involved in the experiment, (3) evaluation of the influence of socio-economic and attitudinal factors on the acquisition of a second language, and (4) investigation of the organizational and pedagogical problems posed by the introduction of second-language teaching at the primary school. (RL)