What are the characteristics of non-native speech and what contributes to the perception of foreign accent by native speakers? In this study, two experiments are conducted to characterize the acoustic features of non-native Japanese production and to examine how these non-native features influence native Japanese perception of foreign accent. In the production experiment, stop consonants and vowel formants were compared between native Japanese speakers and English speakers with 2 and 4 yr of Japanese instruction. The second experiment examines native listener judgments of foreign accent using a visual analog scale. Preliminary analysis reveals that in both stop consonant and vowel production, learners vary considerably from native speakers, specifically in the production of /k/ and /t/ voice onset time, F1 of /e/, and F2 of /u/ and /i/. These features are correlated with judgment ratings by native Japanese listeners. The findings reveal that even after significant experience in the L2 classroom, speakers still struggle to achieve native-like production of various segments, offering insight into specific problem areas which native English speakers might encounter when learning Japanese pronunciation.