The objectives of this study were to examine a body of data collected by five graduate students at the University of Texas at San Antonio and to determine, after a careful analysis of the transcribed utterances, whether all instances of language alternations can be truly considered code-switching strategies and whether those that can be so considered exhibit identifiable linguistic patterns and allow psychologically and sociologically sound interpretations. The emphasis in this paper has been placed on the psycholinguistic and sociolinguistic perspectives of the code-switching phenomenon. The data seem to lend support to the assumption that in fact not all language alternations can be considered "code-switching strategies" proper if we distinguish between utterances containing relexification and others containing sentence constituents from two languages. The former are referred to as "semi-codeswitching" and the latter, true code-switching. The analysis of the examples of true code-switching have yielded some initial evidence that code-switching obeys certain rules of co-occurrence based upon the rules of grammar of the two languages involved in the sense that the code-switching is blocked if it requires the violation of a grammatical rule of either language. As far as linguistic performance is concerned, a total of eleven variables have been identified which seem to act as triggering forces favoring the language alternation. (Author/CFM)