Building on our collective decades of experience studying and consulting on loneliness with companies around the world, we conducted a research program to find out why organizations are struggling to combat work loneliness and to identify the leadership behaviors, social activities, and environments that can make a difference. We studied 1,000 knowledge workers employed by companies in the United States in more than 20 industries, including financial services, healthcare, technology, and manufacturing. Using a measurement tool we developed called the Work Loneliness Scale, we screened people for loneliness before inviting them to participate to ensure that we had at least 200 people in each of three categories: highly lonely (249 participants); moderately lonely (383); and minimally lonely (368). Participants came from all levels of the hierarchy, from young professionals to senior managers, and had a variety of work arrangements: fully in-person (42%), hybrid (37%), and fully remote (21%). We presented the participants with a series of scenarios to test various social opportunities that employers could offer to see which ones resonated the most with workers.