The chapter contributes to the discussion of how linguists can lead communities to adapt successful strategies for maintaining languages. Contact-induced code copying can keep copying varieties strong and thereby contribute to their retention. The framework is the Code-Copying Model. Take-Over copying is in effect when speakers of a primary code (L1) take over copies from a secondary code (L2). Carry-Over copying occurs when speakers of a primary code (L1) carry over copies from this code into their own variety of a secondary code (L2). Both types can strengthen the copying varieties and thereby be felicitous for their maintenance. Copying makes the varieties more viable, e.g. via shared lexical items, shared typological patterns, simplification of grammatical systems. No language has become extinct because of intensive copying. The linguist’s responsibility to document and reconstruct a diachronically and typologically coherent body of data may threaten languages when it gets reflected in the communities efforts to purify their language and make a pre-contact state of the language the target of maintenance or revitalization. Such efforts often reduce the chances for language retention. Strong high-copying varieties and weak purified varieties will illustrate this. The motivation to copy is to accommodate the variety to the communicative needs of the speakers. High-copying varieties can be instrumental in the maintenance of less-copying varieties. In language revitalization, the acquisition of a high-copying variety is easier than the acquisition of a purified variety.