When Microsoft sent everyone to work from home in March 2020, researchers across the company mobilized to study this huge, uncontrolled ‘experiment’. I will discuss the cross-company initiative to coordinate and learn from the wide variety of research projects studying how remote work has affected individuals, teams, and companies. The initiative consists of over 50 research projects, conducted by teams that span a range of disciplines (including engineering, research, marketing, human resources, and facilities) and divisions (including Microsoft Research, Office, Windows, Azure, Xbox, GitHub, and LinkedIn). I will cover some of the over-arching findings around the challenges (and benefits) of work-from-home for collaboration, productivity, and mental well-being. I will then focus on a few studies that I worked on directly – particularly one using Outlook and Teams telemetry data for Microsoft employees, where we try to separate the causal effect of working-from-home from the simultaneous effects of the pandemic. For example, though meeting hours increased, they increased more for those who were already working from home pre-pandemic, suggesting that (in line with previous studies) an individual working from home can be conducive to more focused work, but lead to less collaboration.