This book deals with the consequences of converging and diverging processes and their development in language contact situations. It provides insights into the various forms of language contact and the conditions under which bilingual speakers master their every-day life in bilingual communities. Its nine contributions cover both theoretical and typological aspects, such as the classification of languages, the role of language contact, linguistic complexity and spontaneous speech innovations, and convergence and divergence processes in translation, (morpho)syntax and phonology/phonetics. Taken together, these studies provide challenges for linguistic theories that generalize from situations of monolingualism suggesting instead that a sound linguistic theory cannot be a theory for just one single, isolated language but must be a theory for at least two languages. It must also account for the fact that some structures involved in contact situations are not kept apart but develop in such a way that the distance decreases between the languages involved.