In this paper, we synthesize and discuss our findings on gender from two large-scale studies centered on the use of immersive virtual environments (IVEs) designed with game characteristics, River City and SAVE Science, across the past 12 years. The River City IVE was designed to engage small teams of students, 11-14 years old, in a collaborative scientific inquiry-based learning experience. River City students conducted their scientific investigations in a virtual historical town- populated by themselves, digitized historical artifacts, and computer agents-in order to detect and decipher a pattern of illness that was sweeping through the virtual community. Situated Assessment using Virtual Environments of Scientific Content and Inquiry (SAVE Science) is a study of an innovative system for evaluation of learning in science. SAVE Science consists of a series of virtual environment-based assessment adventures used for assessing both science content and inquiry in middle grades. We will discuss the implication of our findings on gender differences for design and for use of virtual worlds as platforms of learning and assessment in schools. In essence, what we have found is that while girls and boys interact differently with these learning and assessment environments, they both find equal opportunities for success. Our findings indicate that the use of games for learning or assessment does not introduce a gender bias in education as long as attention to design for both is carefully considered.