|The purpose of this study was to examine effects of second language (L2) immersion experiences in a Korean-speaking environment for American English learners of Korean. To accomplish this research purpose, the following hypothesis is constructed; a native English group of learning Korean who had immersed for a longer period as adults would have suprasegmental features, maintaining a greater resemblance to those of native Korean speakers. Seventy participants, divided into four groups(a long-, mid-, short-term immersed group, and 10 native Korean speakers), were asked to produce oral outputs for the evaluation of suprasegmental features of Korean. In general, the longer group was more native-like by having a faster speech rate as well as a comparatively shorter pause duration, smaller pause frequency, and longer duration of the sentence-final syllable. However, the F0 range exerted somewhat different developmental patterns among the groups. These results suggest that even if the acquisition of L2 prosody is affected by the amount of immersion experience, these cues could be developed differently, in which some F0-related cues proved not to be paralleled with other durational ones.