This book is the first extensive study of the categories Hebrew speakers in Israel use for their classification of linguistic variation. It is commonly assumed that Modern Hebrew has no dialects in the traditional sense, despite considerable variation in everyday language use. Its particular sociolinguistic context makes Israel an interesting case to reassess cognitive sociolinguistic theory. This empirical study relies on interviews and experimental data from fieldwork to analyze cognitive processes that shape representations of social groups and linguistic phenomena. It is an original application of Grounded Theory Methodology and introduces the novel method group elicitation and rating task (GERT).