The present study explored the role of constituent frequency and distractor type in complex word learning. Skilled readers were trained to associate novel letter strings with one out of two pictures, with one picture serving as the target, and the other as a distractor. A facilitatory effect of first-constituent frequency was found only in trials where distractors promoted firstconstituent learning, and a facilitatory effect of second-constituent frequency only in trials where distractors promoted second-constituent learning, but not vice versa. Learning occurred in the absence of any pre-existing knowledge about the constituent morphemes and any explicit reference to the constituents during learning. The results point to the important role of constituent frequency and distractor type in novel word learning and provide insights into the mechanisms involved in the implicit acquisition of morphological knowledge in adult learners, that we suspect to be a key aspect of language learning in general.