As a result of the increase in life expectancy in Western societies, the need for elderly people to live with their families (coresidence) is on the rise. The main objectives of this study were to determine the social perception of the advantages and drawbacks of coresidence with elderly people and establish the differences in this perception amongst the coresiding generations. A 20-item scale (Likert-type) was developed to determine beliefs on coresidence. A total of 414 subjects from three generations (207 young people, 146 adults and 61 elderly people) from 207 different families took part in the study. Results: the factorial analysis of the scale entitled "assessment conflict in coresidence with elderly people" (ACE) shows five factors that, together, account for 47.5% of the total variance. The results indicate that there are both positive and negative beliefs, although negative beliefs are the most prevalent. The most prominent positive belief was that the grandparents help to look after their grandchildren. Problems derived from living together and the lack of space were among the negative beliefs. The perception of coresidence with elderly people varied among the generations, and two different patterns were observed regarding the degree of agreement with the statements. In one pattern, the level of agreement gradually increased from the grandchildren generation to the grandparent generation. In the other in two generations, it was similar, and in the third it was different. In general, the parent generation (adults) had the most negative perception of coresidence with elderly people. (Contains 3 tables and 2 figures.)