This study investigates the effect of the language of cartoon films on children’s acquisition of their mother tongue. The language used in the cartoon films under study is Modern Standard Arabic (MSA) while that of the parents and of the environment is Urban Nasiriya Iraqi Arabic (UNIA). The informants of the study consist of three Children who are native speakers of Arabic and whose ages are aged 5,6 and 7 at the beginning of collecting the data of this study. The data collection continues for three years in that it includes the preschool and some school stages. The data collection tool, which is done by the parents from the children, is by means of recordings and daily observation. The children are exposed to the cartoon films for about four to five hours in their daily watching. The methodological procedure consists of describing the language uttered by the informants to prove or refute the hypotheses of the study including that the exposure to the cartoon films has an effect on the informants’ use of MSA, the cartoon films have more effect on the type of dialect used by children compared to parents’ and environment’s dialect, which is UNIA and the theories of informal learning of Marsick and Watkins (1990) and Marsick, Watkins, Callahan, and Volpe (2006) are applicable to acquisition. The study accepts all the hypotheses including that words and sentences used by the informants prove that the dialect used by the informants is MSA, and that the dialect used is affected by the cartoons’ dialect, MSA, to which the children are exposed rather than their parents’ dialect, UNIA.