The present paper deals with Flemish adolescents' informal computer-mediated communication (CMC) in a large corpus (2.9 million tokens) of chat conversations. We analyze deviations from written standard Dutch and possible correlations with the teenagers' gender, age and educational track. The concept of non-standardness is operationalized by means of a wide range of features that serve different purposes, related to the chatspeak maxims of orality, brevity and expressiveness. It will be demonstrated how the different social variables impact on non-standard writing, and, more importantly, how they interact with each other. While the findings for age and education correspond to our expectations (more non-standard markers are used by younger adolescents and students in practice-oriented educational tracks), the results for gender (no significant difference between girls and boys) do not: they call for a more fine-grained analysis of non-standard writing, in which features relating to different chat principles are examined separately.