With the Developmental Lexicon Project (DeveL), we present a large-scale study that was conducted to collect data on visual word recognition in German across the lifespan. A total of 800 children from Grades 1 to 6, as well as two groups of younger and older adults, participated in the study and completed a lexical decision and a naming task. We provide a database for 1,152 German words, comprising behavioral data from seven different stages of reading development, along with sublexical and lexical characteristics for all stimuli. The present article describes our motivation for this project, explains the methods we used to collect the data, and reports analyses on the reliability of our results. In addition, we explored developmental changes in three marker effects in psycholinguistic research: word length, word frequency, and orthographic similarity. The database is available online.Keywords Visual word recognition . Development . Mega studies . Lexical decision . NamingThere is an extensive body of research on the visual word recognition processes in skilled adults (e.g., Balota et al., 2007). On the basis of this research, several computational models have been developed that account for many of the benchmark effects observed in word processing tasks such as lexical decision (LD) or naming (e.g., Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001;Harm & Seidenberg, 2004;Perry, Ziegler, & Zorzi, 2007). Most of these models, however, only aim at explaining the reading behavior of proficient adults who have already acquired the ability to read. In recent years, some efforts have been made to bring interindividual differences into the picture (Andrews & Lo, 2012; Adelman, Sabatos-DeVito, Marquis, & Estes, 2014;Kuperman & van Dyke, 2013;Yap, Balota, Sibley, & Ratcliff, 2012). Arguably, however, the most pronounced differences between readers are intra-individual in nature: Children are not born with the ability to read but need years of extensive practice in order to learn it. And even during adulthood, profound changes take place in lexical and sublexical processing (Balota, Cortese, Sergent-Marshall, Spieler, & Yap, 2004;Ratcliff, Perea, Colangelo, & Buchanan, 2004). Yet, developmental models of the visual word recognition process are still rather scarce (but see Pritchard, Coltheart, Marinus, & Castles, 2016;Ziegler, Bertrand, Lété, & Grainger, 2014). One of the main reasons for this is that very few studies have been conducted that investigate visual word recognition across the lifespan within a coherent framework. Thus, at present, the empirical data that are necessary to feed any computational modeling efforts are missing.The present article describes the Developmental Lexicon Project (DeveL), which provides a linguistic database for 1,152 German words including behavioral measures of how they are processed at different age groups across the lifespan. Extending the logic and methodology of existing mega studies on visual word recognition (Balota et al., 2007;Balota, Yap, Hutchison, & Cortese, 2012;...