This paper will outline the theoretical and methodological aspects of comparative research on youth language (with a special focus on the pluricentric Spanish language) in order to arrive at a reliable description of the characteristics and the contextual conditions of the emergence of youth language in different socio-cultural situations as well as their underlying aims, conditions and possible parameters of investigation in accordance with the (pragmatic) identity functions of youth language. Three types of comparison will be established – reflecting the typological, the contrastive and the diatopic-contrastive approach. A particular focus is on diatopic-contrastive research, since comparison of regional varieties of youth language within one language has not played a major role in the debate about youth language so far.