Heritage language (HL) is a linguistic system that arises in the context of early childhood bilingualism, both sequential and simultaneous, when one of the languages is not fully acquired. The performance of speech acts in HLs is yet to be understood, and this dissertation is a first step in this direction. The study investigates the pragmatic competence of adult Heritage Russian (HR) speakers dominant in American English by focusing on their ability to comprehend and produce requests for favor that appeal primarily to the addressee's good will. The data were collected through a questionnaire and role-play enactments in native-speaker (NS) and HR populations. A comparison with the established NS baseline indicates that HR speakers lack full knowledge of Russian-specific linguistic conventions and sensitivity to finer aspects of illocutionary meanings. Nevertheless, they can perform speech acts because they efficiently combine pragmatic and structural linguistic knowledge from their two languages. This combination of linguistic material is unique to HR speakers and involves internal restructuring of Russian pragmatic norms and linguistic convergence conditioned by language contact. Specifically, HR speakers re-analyze the Russian impersonal modal "mozno" (which normally marks permission requests) as a generalized marker of any request. The influence of English leads HR speakers to overuse politeness marker "pozalujsta" in indirect requests, contrary to NS preference. Also unlike NS, HR speakers tend to avoid the negative particle "ne" in indirect requests with a finite modal (due to incomplete acquisition and transfer) and to orient their requests to the speaker (transfer effect). Combination of linguistic material leads to the emergence of new pragmatic conventions, specific to HR, which involve "mozno" + "pozalujsta" for requests addressed to peers and embedding under performative + "pozalujsta" for formal situations. The resulting composite pragmatic matrix of HR requests proposed in this study is based on an abstract linguistic structure that combines Russian and English pragmatic conventions. Requests produced by HR speakers do not involve overt code-switching at the surface, but exhibit cross-linguistic influence at the abstract level. The abstract convergence of two languages within HL pragmatics indicates that languages in contact interact within all levels of an utterance. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]