Eye-tracking is primarily used as a tool to capture attentional processes in second language (L2) research. However, it is feasible to design visual displays that can react to and interact with eye-movements in technology-mediated contexts. We explored whether gaze-contingency can foster L2 development by drawing attention to novel words reactively during reading. In particular, we investigated whether the acquisition of lexis can be facilitated by interactive glosses, that is, making glosses visually salient when triggered by fixations on a target word. We found that interactive, gaze-contingent glosses led to more and longer fixations at target words and glosses but did not lead to superior performance in recognition scores. We observed, however, an interaction between interactivity and form recognition, with more gloss fixations being associated with better performance under the interactive, but with worse outcomes in the non-interactive, condition. We attributed this difference to distinct motivations for viewing glosses in the groups.