The study of communication strategies can provide insights into the ways in which interlanguage changes and develops as language learners become increasingly proficient in the target language. This article describes an investigation centered on the communication strategies used by two groups (intermediate and advanced) of Spanish-speaking students of English to express lexical meaning. Two different tasks, one conskting of answering structured questions and the other a simulated communication situation, were used to elicit data from the students. Data were collected at two different times, once at the beginning of the term and again five weeks later. Proficiency level, task, and time were the independent variables and three types of communication stmtegies (transfer, overgeneralization, and task-influenced) were the dependent variables. It was found that the unstructured task elicited significantly more transfer strategies from both groups of students, and that there was a significant interaction between time and proficiency level with respect to the use of task-influenced strategies—the advanced group used a greater mean proportion of task-influenced strategies than the intermediate group at Time1, while the intermediate group used a greater mean proportion of this type of strategy at Time2. A post hoc analysis of these data suggests that students of a language may go through a period of maximum exploitation of task-influenced strategies which peaks and then drops off as they become more proficient in the language.