Immersive systems, like Augmented and Virtual Reality, offer new paradigms fordigital interaction, but confining users to a single reality often presents drawbacksfor complex tasks. Cross-Reality systems, which integrate multiple realities into asingle experience, have significant potential to enhance existing professional workflows by combining the unique strengths of physical and virtual environments. Thisdissertation investigates how Cross-Reality can enhance professional workflows byusing the traditional office as a primary use case, focusing on the central question:How can CR enhance existing workflows in physical settings by extendingthe physical environment with virtual content and environments?To address this, the dissertation presents a body of empirical work structuredaround isolating and investigating one core design challenge for each of the threeprimary types of Cross-Reality systems. The work first addresses transitionalCross-Reality systems, which allow users to switch between different realities, byexamining how to design effective transitions. It demonstrates that in task-drivenscenarios, users prioritize efficient transitions that minimize cognitive disruptionover more elaborate or interactive ones. Next, the dissertation tackles the fundamental problem of unwanted occlusion in Augmented Virtuality, a form of substitutional Cross-Reality systems, which integrate objects from one reality intoanother. It introduces and evaluates technical strategies to ensure physical toolsremain accessible within virtual spaces, revealing a critical trade-off between theefficacy of these solutions and user experience factors like cybersickness. Finally,the research explores multi-user Cross-Reality systems that enable collaborationbetween multiple users who may be experiencing different degrees of virtualitysimultaneously, and the complexities of enabling collaboration across multiplestages, underscoring the unique challenges of supporting shared awareness andmanaging asymmetric roles.These findings are grounded by a detailed analysis of the underlying hardware, which highlights how technical and perceptual issues inherent to VideoSee-Through and Optical See-Through Head-Mounted Displays directly impactthe feasibility and design of Cross-Reality systems. The overarching contributionof this dissertation is to provide a set of empirically-grounded design principlesfor applying Cross-Reality in productivity-focused environments. By shifting thedesign focus from entertainment to pragmatic qualities, this work offers valuableinsights into creating Cross-Reality systems that genuinely enhance workflows, prioritizing efficiency, usability, and seamless interaction while navigating technical