Adult English-L1 (n = 20) and English-L2 (n = 32) experimental groups were given a novel containing nonce words to read within two weeks to investigate whether the reading of fiction can induce a state of incidental vocabulary acquisition. After reading, an unexpected meaning recall translation assessment measuring acquisition of 49 target nonce words was administered, followed by an open-response reflective questionnaire. Assessment results indicated that English-L1 speakers were better than English-L2 speakers at incidentally acquiring vocabulary through the reading of fiction. Furthermore, results indicate that only three encounters with unknown words may be needed to encourage acquisition if the reading of a target text is enjoyable or of importance to the reader. Comparing acquisition results for English-L1 and English-L2 experimental groups to English-L1 (n = 13) and English-L2 (n = 27) control groups, however, indicated vocabulary acquisition could not be completely attributed to incidental acquisition, with the English-L1 control group being more successful in guessing the meanings of unknown words than the English-L2 control group. Post hoc interviews with both the English-L1 and English-L2 experimental groups indicated a difference in English-L1 speakers' and English-L2 speakers' perception of nonce words, which may have affected assessment outcomes. The results of the current investigation suggest that the use of nonce words could confound acquisition results if participants realize that the nonce words are proxies representing already known real words or give the nonce words a different status than real words. Results warrant the use of control groups in incidental vocabulary acquisition research regardless of whether real or nonce words are used as targets.