In 1962, Peal and Lambert published the results of a study comparing bilingual and monolingual children on various measures of intelligence and achievement. Their findings were surprising, at least in light of certain assumptions that had been prevalent in child psychology up to that time. They found no evidence to indicate any sort of intellectual deficiency in bilingual children. The performance of bilinguals on all measures was either equivalent or superior to that of their monolingual comparison group. These results were in clear contradiction to a belief that had come to be accepted as truism by psychologists and laymen alike, especially in North America: The acquisition of two languages in childhood impairs intellectual development-it leads to mental confusion or difficulties in coordinating language and thought in children. The results obtained by Peal and Lambert suggested that there are no detrimental effects of bilingualism, and there may even be some cognitive advantages.