This study presents a shifting pattern in the use of second person singular pronouns of address in Russian by adult Russian immigrants in Toronto. The newly developing pattern is treated as a case of L1 attrition. The observed changes to the pronominal system of Russian are discussed in the framework typically employed in language attrition literature, with reference to various linguistic phenomena such as lexical transfer, simplification of morphosyntax, markedness theory and competence vs. performance attrition. Reference is also made to sociolinguistic phenomena such as L1/L2 use in sociolinguistic domains, ethnolinguisitic vitality and shift in cultural identity.