We present evidence on how generative AI changes the work patterns of knowledge workers
using data from a 6-month-long, cross-industry, randomized field experiment. Half of the 6,000
workers in the study received access to a generative AI tool integrated into the applications they
already used for emails, document creation, and meetings. We find that access to the AI tool during
the first year of its release primarily impacted behaviors that could be changed independently and
not behaviors that required coordination to change: workers who used the tool spent 3 fewer hours,
or 25% less time on email each week (intent to treat estimate is 1.4 hours) and seemed to complete
documents moderately faster, but did not significantly change time spent in meetings.
