This study measures whether number and type of morphemes in an elicited imitation string results in a greater number of modifications with L2 experience. Rationale is drawn from L2 working memory processing limitations at distinct levels of proficiency. 38 subjects (L2 Spanish university students) comprise three proficiency groups: beginning, undergraduate majors and graduate students. Number of morphemes was varied within each syllable count; and responses were either correct or modified (lexemically/inflectionally as deletions or substitutions). Two way ANOVAs determined significance between mean proportions for each group. Findings indicate that increases in number of morphemes yielded significant differences; and that while the lowest proficiency group produced higher proportions of lexical deletions, the more advanced groups' modifications were inflectional substitutions.