This article reports an experiment on the implicit learning of second language stress regularities, and presents a methodological innovation on awareness measurement. After practising two-syllable Spanish words, native Cantonese speakers with English as a second language (L2) completed a judgement task. Critical items differed only in placement of stress. We assessed participants' awareness of the hidden stress regularities by verbal reports and a novel methodology: inclusion-exclusion production tasks adapted from Jacoby (1991) and from Destrebecqz and Cleeremans (2001). Participants who remained unaware of the underlying regularities nevertheless performed significantly above chance in identifying correctly pronounced novel words. We conclude that L2 word stress regularities may be learnt implicitly.