In recent decades, the work of teachers has been carried out in classrooms characterised by a high degree of diversity, necessitating the provision of pedagogical responses that promote the inclusion of students. This article is derived from the research, development and innovation (R+D+I) project 'Intergenerational Professional Development in Education Implications for the Professional Initiation of Teachers (DePrInED) and aims to analyse how teachers at compulsory education recognise, characterise and conceptualise the diversity and needs of students. A mixed methodological approach was employed, with information collected through focus groups and interviews with a total sample of 147 teachers from different educational levels (young, senior and retired). Thematic analysis, combined with a comparative analysis, was employed to analyse the data using ATLAS.ti software. The main categories analysed dealt with students' needs and their own diversity. The study's primary findings suggest that, in comparison to their retired counterparts, both young and veteran teachers make greater reference to the diversity and needs of students, and emphasise the scarcity of resources and support to effectively address the diversity of students in the classroom. Experienced teachers are found to make more frequent references to diversity and students' needs, while retired teachers make these references less often. This finding assumes particular significance in light of the paucity of studies that adopt a generational perspective to analyse how teachers perceive diversity.