This paper evaluates the pedagogic aspects of the Yugoslavian Serbocroatian-English Contrastive Project. The project carried out a contrastive analysis of the phonological, morphological, syntactic and lexical structures of English and Serbocroatian, and an error analysis in the use of English parts of speech and sentence parts. The investigation noted deviations in the use of parts of speech of a morphological or lexical nature and deviations in production of grammatical sentences. One major cause of such deviations is interference from the native language; incorrect analogy in applying a general rule to all cases, interference from another foreign language, errors from the transitional phase of language learning, and incomplete mastery of the target language are other causes of errors. The contrastive results were first tested using the findings of error analyses. The pedagogical material was tested in actual classroom teaching. Systematic experiments with written multiple-choice, transformation and translation tests given to advanced learners of English checked the research by revealing language errors or interference. Errors found were classified and charted, and details from the report on the present tense illustrated the importance of the testing and of contrastive analysis to pedagogy. (CHK)