In 2018, Cortex was largely vendor-driven, and almost no one other than maintainers could run it. Its docs were lacking; you had to read the code instead. While that might be acceptable for a new project, it's not for wide adoption. Over the last few years, since joining the CNCF, we have put a focus on building a vibrant community. It was a long and arduous journey, but we're very happy with the healthy community we have today, with maintainers from 5 different companies and a 5x increase in activity on the Cortex Slack and GitHub! While our _public_ adopters document lists more than 15 companies, with several providing Cortex as a service, we have a lot more companies running it, from international banks and Fortune 50 enterprises to small startups. In this talk, we will walk through the key changes we made and how our philosophy on community-building helped us thrive and led to fruitful collaboration with sibling projects Thanos and Prometheus.