This volume interfaces three fields of linguistics rarely discussed in the same context. Its underlying theme is linguistic variation, and the ways in which historical linguists and dialectologists may learn from insights offered by typology, and vice versa. The aim of the contributions is to raise the awareness of these linguistic subdisciplines of each other and to encourage their cross-fertilization to their mutual benefit. If linguistic typology is to unify the study of all types of linguistic variation, this variation, both diatopic and diachronic, will enrich typological research itself. With the aim of capturing the relevant dimensions of variation, the studies in this volume make use of new methodologies, including electronic corpora and databases, which enable cross- and intralinguistic comparisons dialectally and across time.