Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Electronic health (eHealth) literacy was conceptualized in 2006 as the ability of Internet users to locate, evaluate, and act upon online health information. eHealth advancements have cultivated transactional opportunities for patients to access, share, and monitor health information. However, empirical evidence shows that existing models and measures have limited theoretical underpinnings that reflect the transactional capabilities of eHealth. The current manuscript describes a conceptual model based on the Transactional Model of Communication (TMC), in which eHealth literacy is conceptualized as dynamic, cyclical, and shaped by contextual factors. Objective: This study systematically examined eHealth literacy definitions, models, and measures to propose a refined conceptual and operational definition based on the TMC. Methods: An adapted version of Walker and Avant’s concept analysis method was used to guide the systematic review of eHealth literacy definitions (N = 10), rating scales (N = 6), models (N = 4), and peer-reviewed model applications (N = 16). An inductive cluster analysis was conducted to identify salient themes across definitions. Dimensions, antecedents, and consequences within models and measures were extracted, deductively analyzed based on codes consistent with the TMC. Results: A disconnect remains between operational skills in definitions and the literacies within models and measures. Theoretical underpinnings of eHealth literacy remain dismal, although recent measures incorporate tenants of the social cognitive theory. Despite the transactional capabilities of eHealth, the role of “communication” remains underdeveloped and limited to the physical and cognitive processing of two-way interactions that occur in eHealth. Conclusions: The Transactional Model of eHealth Literacy (TMeHL) and a corresponding definition is proposed. eHealth literacy is a hierarchical and multidimensional intrapersonal skillset that mediates the cyclical effect of contextual factors (i.e., user-oriented, task-oriented) on factors related to patient activation. The intrapersonal skillset is comprised of four eHealth literacies, which correspond with operational behaviors central to defining eHealth literacy: functional (i.e., locate, understand), communicative (i.e., exchange), critical (i.e., evaluate), and translational (i.e., apply). As posited by the model and consistent with the TMC, this four-dimensional intrapersonal skillset counteracts the negative effect of noise produced by preceding contextual factors, to ultimately influence patient activation and expectations of future eHealth experiences.