The lexical representation of compound words in speech production is still under debate. While most studies with healthy adult speakers suggest that a single lemma representation is active during compound production, data from neuropsychological studies point toward multiple representations, with activation of the compound's constituent lemmas in addition to the compound's lemma. This study exploits the cumulative semantic interference effect to investigate the lexical representation of compounds in speech production. In a continuous picture naming experiment, category membership was established through the compounds' first constituents (category animals: "'zebra' crossing," "'pony' tail," "'cat' litter" …), while the compounds themselves were not semantically related. Moreover, pictures depicting the compounds' first constituents ("zebra," "pony," "cat" …) were presented as a control condition. As expected, naming latencies within categories increased linearly with each additionally named category member when producing monomorphemic words, which is interpreted as increasing interference during lexical selection. Importantly, this cumulative semantic interference effect was also observed for compounds. This indicates that the lemmas of the compounds' first constituents were activated during compound production, causing interference due to their semantic relationship and thereby hampering the production of the whole compound. The results are thus in line with the multiple-lemma representation account (Marelli et al., 2012). We argue that the apparent contradiction between results of previous studies with healthy adult speakers and our current study can be explained by the different experimental paradigms used.