A study investigated whether markedness relationships within a target language influence the degree of difficulty in acquisition. The Intralingual Markedness Hypothesis was developed, stating that if structures in the target language differ from those in the native language, and if those structures in the target language are in a markedness relationship, the more marked structures will be more difficult to acquire than the less marked structures. Fourteen adult native speakers of Spanish each read aloud 435 topically unrelated sentences, each containing one of three target onsets ("sl, sm, sn") not found in Spanish. Degree of difficulty was measured by the frequency of epenthesis before the onsets. Statistical analysis of results revealed that the mean frequency of epenthesis before "sl" was significantly lower than that before the other two, supporting the Intralingual Markedness Hypothesis. A brief bibliography and a brief list of sentences from the study are appended. (MSE)