This study undertakes a comparative analysis of the negative stereotypes of older persons described by young and older adult university students at the University of Castilla-La Mancha. This study is innovative in that it compares three analytical perspectives: the perception of young students (18-27 years); the perception of older adult students (50 years and above) regarding older persons (hetero-stereotypes); and, finally, the perception of older adult students with regard to themselves as part of the group of older adult students (self-stereotypes). The sample is made up of 460 young students and 148 older adult students who completed the Questionnaire on Negative Ageing Stereotypes (QNAS), comprising three dimensions: health; character and personality; and social relationships and motivation. A statistical analysis was subsequently carried out using the independent samples t-test in the IBM Statistics 19.0 program. Of note among the principal results is the low level of negative stereotypes reported among the groups studied, as well as the existence of significant differences in their means, which indicate that the negative stereotypes of the groups differed. The most stereotyped of the dimensions analyzed was character and personality. In contrast, the least-stereotyped dimension was that of social relationships and motivation. Finally, the dimension of health occupied an intermediate position. With regard to the three perspectives studied, the older adult group (hetero-stereotypes) was the most stereotyped, followed by the young students and, finally, the older adult students with reference to self-stereotypes.