Contact between the Western culture and African indigenous cultures, during the Colonial era, resulted in directional cultural changes in these cultural systems. One of the Gikuyu customs most affected by this change was the rite of passage from childhood into adulthood. This study, which was carried out through the standard anthropological technique of participant - observation and focused interviews, examined the form of change that this rite underwent and the effect of this change on the Gikuyu society. Through the cross-sectional method I traced this change in three generations based upon descent from a living Gikuyu elder.The study shows that the age-grading system, the ceremonies and functions associated with the traditional rite of passage into adulthood has virtually vanished. Female clitoridectomy has been replaced by the onset of menarche as the rite of passage into adulthood. Male circumcision has lost its significance as a rite of passage from childhood to adulthood, and is mainly practised as a rite of passage from primary school to secondary school due to peer-pressure. The disappearance of the functions associated with the traditional rite of passage into adulthood has resulted in an inadequate preparation for the adult roles. The consequence has been a high rate of social problems and a widespread dissatisfaction with the current social life among the Aa-Gikuyu. / Department of Anthropology