This dissertation utilized a multiple case study design to explore how advanced learners synthesize information about ill-structured topics when reading-to-learn and reading-to-do on the Web. Eight graduate students provided data in the form of think-alouds, interviews, screen video, digital trails, and task artifacts. Data analysis was based on abductive coding, first examining synthesis through the theoretical lenses of reading comprehension, Cognitive Flexibility Theory on the Web, and creativity, followed by a constant comparative exploration of emergent phenomenon in the data. The empirical findings from this study provided the foundation for a Theory of Web-mediated Synthesis comprised of interdependent elements--divergent keyword search phrases, synthesis for meaning, in-the-moment insights, repurposing, reinforcement and note-taking--which together lead to creative syntheses. Illustration and elaboration of these elements are provided in the context of two in-depth case studies. In doing so, this dissertation provides a post-comprehension lens through which to better explore and understand generative reading and learning activities on the Web. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]