Adult second language (L2) learners often have difficulty perceiving and producing L2 speech segments with native-like accuracy. The Speech Learning Model (SLM; Flege 1995) attributes this to perceptual distance between native (L1) and L2 segments, the Perceptual Assimilation Model (PAM; Best 1995; Best and Tyler 2007) to L1 assimilation of L2 segmental contrasts. In a novel extension of these models, we examined whether experience with an L1 suprasegmental duration contrast can affect performance on L2 segmental vowel distinctions that are non-contrastive in the L1. Serbian employs an unusual type of relevant suprasegmental duration distinction, specifically morphological alternations in pitch accented syllable duration. We assessed L1-Serbian participants' perception and production of L2-English /i-i/ versus /ae-epsilon/, which involve both spectral and temporal distinctions but differ in magnitude of their temporal difference. The results indicate that experience with L1 syllable durations conditioned by pitch-accent systematically influences perception and production of L2 vowel contrasts.