A long tradition of adoption of innovations research in the information systems context suggests that innovative information systems are typically adopted by the largest companies, with the most slack resources and the most management support within competitive markets. Additionally, five behavioral characteristics (relative advantage, compatibility, observability, trialability, and complexity) are typically associated with demand-side adoption. Recent market trends suggest, though, that additional influences and contingencies may also be having a significant impact on adoption of innovative information systems-on both the supply and demand-sides. The primary objective of this dissertation is to extend our theoretical knowledge into a context where consumer influence is a key consideration. Specifically, this dissertation focuses on the Personal Health Record (PHR) and patient portal market due to its unique position as a mediator between supply (ambulatory care clinic) and demand-side (patient and health consumer) interests. Four studies are presented in this dissertation and include: 1) an econometric examination of the contingencies associated with supply-side (ambulatory care clinic) adoption of patient portals, 2) a behavioral assessment of patient PHR adoption intentions, 3) an integrated latent variable and discrete choice evaluation of consumer business model preferences for digital services (PHRs), and 4) an experimental evaluation of how digital service (patient portal) feature preferences are impacted by assimilation and contrast effects. The primary contribution of this dissertation is that adoption (and adoption intentions) of consumer information systems are significantly impacted by: 1) supply-side adoption contingencies (even when controlling for dominant-paradigm adoption of innovation characteristics), and 2) demand-side consumer preferences for business models and features in the context of assimilation-contrast (even when controlling for individual differences). Overall, this dissertation contributes a new understanding of how contingent factors, consumer perceived value, and assimilation/contrast of features are impacting adoption of consumer information systems. [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.]