Mopan is a language of the Yucatecan Maya family, spoken by about 10 000 people in the Eastern Pet\\233n, Guatemala, and Southern Belize. This study focusses at the native language of the 3 000 Belizean Mopan speakers, who, after 2 centuries of contact with the Spanish language and culture, are experiencing now, as fourth generation immigrants a second contact stage with Belizean Creole English. Belizean Mopan is unusual among the Mayan languages in displaying only slight structural Spanish interferences. The systematic study of Mopan lexicon reveals that Spanish influence has not penetrated in an equal measure the various domains of importance to Mopan society. The persistence of the native lexicon related to the studied domains gives an indication of continuity in various aspects of traditional Mopan culture. In the section on phonological interferences a significant finding concerns a sound change in exclusively Spanish loanwords, which indicates that Mopan speakers possess some unconscious awareness of the foreign status of part of their lexicon. A large portion of the research was devoted to the question of how Mopan speakers incorporated the different borrowed parts of speech into the Mopan linguistic structure. Among the interesting characteristics of the grammatical interference analysis are the neutral status of nouns, the incorporation of loanverbs into an agentive subclass of the intransitive verb category, the native character of comparative constructions, the doublet constructions in the use of discourse markers.