Purpose: The purpose was to determine the number of semantic neighbors, namely, "semantic set size," for 88 nonobjects (J. F. Kroll & M. C. Potter, 1984) and determine how semantic set size related to other measures and age. Method: Data were collected from 82 adults and 92 preschool children in a discrete association task. The nonobjects were presented via computer, and participants reported the first word that came to mind that was meaningfully related to the nonobject. Words reported by 2 or more participants were considered semantic neighbors. The strength of each neighbor was computed as the proportion of participants who reported the neighbor. All data are provided online in a Microsoft Excel file accompanying this article (the data file can be found accompanying this article online at http://jslhr.asha.org). Results: Results showed that semantic set size was not significantly correlated with objectlikeness ratings or object decision reaction times from J. F. Kroll and M. C. Potter (1984). However, semantic set size was significantly negatively correlated with the strength of the strongest neighbor(s). In terms of age effects, adult and child semantic set sizes were significantly positively correlated and the majority of numeric differences were on the order of 0-3 neighbors. Comparison of actual neighbors showed greater discrepancies; however, this varied by neighbor strength. Conclusions: Semantic set size can be determined for nonobjects. Specific guidelines are suggested for using these nonobjects in future research.