There is broad consensus that printed complex words are identified on the basis of their constituent morphemes. This fact raises the issue of how the word identification system codes for morpheme position, hence allowing it to distinguish between words like "overhang" and "hangover", and to recognize that "preheat" is a word, whereas "heatpre" is not. Recent data have shown that suffixes are identified as morphemes only when they occur at the end of letter strings (Crepaldi, Rastle, & Davis, 2010, "Morphemes in Their Place: Evidence for Position-Specific Identification of Suffixes," "Memory & Cognition, 38", 312-321), which supports the general proposal that the word identification system is sensitive to morpheme positional constraints. This proposal leads to the prediction that the identification of free stems should occur in a position-independent fashion, given that free stems can occur anywhere within complex words (e.g., over"dress" and "dresser"). In Experiment 1, we show that the rejection time of transposed-constituent pseudocompounds (e.g., "moonhoney") is longer than that of matched control nonwords (e.g., "moonbasin"), suggesting that honey and "moon" are identified within "moonhoney", and that these morpheme representations activate the representation for the word "honeymoon". In Experiments 2 and 3, we demonstrate that the masked presentation of transposed-constituent pseudocompounds (e.g., "moonhoney") facilitates the identification of compound words ("honeymoon"). In contrast, monomorphemic control pairs do not produce a similar pattern (i.e., "rickmave" did not prime "maverick"), indicating that the effect for "moonhoney" pairs is genuinely morphological in nature. These results demonstrate that stem representations differ from affix representations in terms of their positional constraints, providing a challenge to all existing theories of morphological processing. (Contains 7 tables and 3 footnotes.)