Dealing with uncertainty is a critical part of human decision-making and confidence reflects one's belief about the relative likelihood that various outcomes occur when making decision under uncertainty. Unfortunately, confidence often deviates from the actual quality of the decision, leading to under- or over-confidence. Calibration, the agreement between confidence and decision quality, captures how one's confidence deviates from objective decision quality. Confidence and user calibration have been considered as critical outcome variables in human judgment and decision-making but did not receive too much attention from IS discipline. Drawing on Social Cognitive Theory, this dissertation proposes a conceptual framework to examine confidence and user calibration in information systems use. Then two experiments were conducted to empirically evaluate the proposed conceptual framework. Specifically, Essay one reviews the literature on confidence and calibration and draws on social cognitive theory to propose a conceptual framework, which guides the following empirical studies. Essay two empirically examines the effects of two system characteristics (visualization and interactivity), along with task difficulty, on decision accuracy, confidence, and calibration in financial decision-making. Essay three empirically examines how visualization and interactivity interact with task difficulty and individual difference (gender, need for cognition, and self-monitoring), and jointly influence decision quality, confidence, user calibration, and subsequent behavioral intention in online shopping context. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]