This is the dataset of a lexical decision task performed in English as L2 by Dutch L1 participants. The dataset contains raw RTs and accuracy scores for the stimuli and participant information. The 800 word stimuli in the experiment are taken from the Ghent Eyetracking COrpus (Cop et al., 2017). A detailed method section on the task can be found in the supplementary material of Dirix & Duyck (2017). In this study, the dataset was used to compare the L1 and L2 word-level age-of-acquisition effect between lexical decision and eye movement measures. The dataset has also been used in a more general comparison of lexical decision RTs and timed eye movement measures (see Dirix et al., in press). ---------- References Cop, U., Dirix, N., Drieghe, D., & Duyck, W. (2017). Presenting GECO: An eyetracking corpus of monolingual and bilingual sentence reading. Behavior Research Methods, 49(2), 602–615. https://doi.org/10.3758/s13428-016-0734-0 Dirix, N., Brysbaert, M., & Duyck, W. (in press). How well do word recognition measures correlate ? Effects of language context and repeated presentations. Behavior Research Methods. https://doi.org/https://doi.org/10.3758/s13428-018-1158-9 Dirix, N., & Duyck, W. (2017). The first- and second-language age of acquisition effect in first- and second-language book reading. Journal of Memory and Language, 97, 103–120. https://doi.org/10.1016/j.jml.2017.07.012