The 2019 Common Alerting Protocol (CAP) Implementation Workshop was held 17 – 18 September, in Mexico City, Mexico China. The host of this Workshop was the Mexico City Secretariat of Integral Risk Management and Civil Protection. CAP Implementation Workshops focus on emergency alerting as enabled by the CAP standard, ITU-T Recommendation X.1303. At the Workshops, implementors of CAP and associated organizations discuss common issues and how best to expand adoption of CAP.