Adult Japanese learners of English (JLEs) are often stereotyped as being unable to produce or perceive the English phonemes /l/ and /r/. This study analyzed acoustic samples of /l/ and /r/ obtained from intermediate-level Japanese speakers in two variable contexts: word positions (initial/final) and task type (controlled/free). These tokens were subjected to acoustic analysis which is one way of comparing oral productions of native and non-native English speakers. Previous research has identified a lowered third formant (F3) as the hallmark of an American English /r/ as produced by a native speaker, independent of word position or task type. The results indicate that participants can produce appropriate and statistically significant differences (p<.001) between these two phonemes across word position and task type. Other findings indicate that neither task type nor word position had a significant effect on F3 values. These results indicate that Japanese speakers of English may have the ability to distinguish /l/ from /r/ without specialized pronunciation training, but these differences are less dramatic as identified by F3 frequency values that those produced by native English speakers when producing these contrasting phonemes. In most tokens, however, large effect sizes remained between JLE productions and NES standards.