This study investigates the extent to which L2 learners with different L1 backgrounds are sensitive to phonetic information contained in the visual cues to a novel phonetic contrast (labial/labiodental contrast), and the degree to which this sensitivity can be increased via intensive training. 36 Spanish-L1 and 47 Japanese-L1 learners of English were initially tested on their perception of the /b,p/-/v/ contrast in audio, visual and audiovisual modalities. The Spanish-L1 learners showed better performance overall, and much greater sensitivity to visual cues to the contrast. The Japanese-L1 group achieved higher scores in the AV than in the A test condition. In Study 2, 39 of the Japanese-L1 learners undertook ten sessions of either auditory or audiovisual intensive training before being tested again. Both groups improved significantly, with a greater improvement seen for audiovisually-trained learners. The benefit from AV training did not depend on learners' sensitivity to visual cues prior to training.