The topic of the volume is the contrast between borrowable categories and those which resist transfer. Resistance is illustrated for the unattested emergence of grammatical gender, the negligible impact of English and Spanish on the number category in Patagonian Welsh, the reluctance of replicas to borrow English but. MAT-borrowing does not imply the copying of rules as the Spanish function-words in the Chamorro irrealis show. Chamorro and Tetun Dili look similar on account of their contact-induced parallels. The languages of the former USSR have borrowed largely identical sets of conjunctions from Russian, Arabic, and Persian to converge in the domain of clause linkage. Resistance against and susceptibility to transfer call for further investigations to the benefit of language-contact theory.