This thesis is an attempt at discovering the use made of the mass medi a in both the English a nd Welsh languages by bilingual children in a Welsh~speaking area of Wales. Two investigations were conducted ·the first in November 1978 when the children were 10 years old, and the second three years later, involving the same children. Each investigation consisted of a questionnaire, together with attitude and attaiment tests in both languages. The questionnaire investigated the children's linguistic background, and their use of the various mass media~ The tests administered were tests of attainment-of spelling of word recognition and of attitude. In additlon, the children were asked to keep a diary of their television viewing for a week during both investigations.: It was suspected that the children's use of the mass media in the two languages would depend on their differing linguistic backgrounds; consequently their answers to the language background questions or the first questionnaire wer e used t o divide them· into gr oups having broadly similar linguistic backgrounds using a technique known as Cluster Analysis. Following the second investigation, the whole sample was examined for changes in the use made of the mass media , and for changes of attainment in and attitude towards both languagest over the three year period. It was found that the children made much more use of the mass media in English than in Welsh both at 10 and 13 years old, and that their attitude towards the two languages changed consider ably during the three years. Their attitude towards English became more favourable as they grew older, while their attitude towards Welsh became less favourable . When we examined the groups for differences, it was found that the stronger the English linguistic background of a group, the less likely were the members to make much use of the Welsh language mass media. The implications of the results are discussed in terms of the role of the mass media in creating a bilinguals ociety and in complementing a bilingual educational policy.