The National Public Alerting System (NPAS; French: Système national d'alertes à la population), branded as Alert Ready (French: En Alerte), is the national warning system in Canada, broadcast to Canadian television, radio, and wireless devices.

The system consists of infrastructure and standards for the presentation and distribution of public alerts issued by federal or provincial/territorial government authorities (particularly public safety authorities)—such as for weather emergencies, Amber alerts, and other emergency notifications—through all broadcasters and last-mile distributors in the affected region, including television stations, radio stations, television providers, and mobile networks in the affected region. The system is based upon the Common Alerting Protocol (CAP; called the Canadian Profile of the Common Alerting Protocol, CAP-CP), while wireless alerts (Wireless Public Alerting System) use a Canadian variant of the Wireless Emergency Alerts (WEA) standard adopted in the United States.

Alert Ready officially launched on 31 March 2015; it distributes alerts to broadcasters and other parties through its central technical infrastructure—called the National Alert Aggregation and Dissemination (NAAD) system—which was developed and is operated by Pelmorex Media—owner of The Weather Network. Pelmorex is also responsible for public awareness campaigns surrounding the system. By order of the Canadian Radio-television and Telecommunications Commission (CRTC), all terrestrial radio and television stations, digital multichannel television providers, and mobile network operators using LTE technology or newer, are required to participate in the NPAS.

Alert Ready has faced criticism, particularly due to wireless alerts being handled under a blanket category with no opt-outs on its smartphones running unmodified operating systems (as opposed to the severity-based system used by the U.S. WEA system), and criticism over Amber alerts (particularly in Ontario) being issued province-wide rather than geographically targeted to relevant regions. In April 2020, the RCMP faced criticism for not understanding and being slow to work with local officials in use of the system to warn of an active gunman, which had attacked multiple locations in the province of Nova Scotia.

Environment and Climate Change Canada also maintains Weatheradio Canada, which transmits weather information and hazard alerts. Unlike Alert Ready, it utilizes Specific Area Message Encoding (SAME)—the same protocol used by NOAA Weather Radio and the Emergency Alert System in the United States.

Various attempts had been made in the 20th and 21st centuries to establish a public alert system in Canada, by both departments of government and by television broadcasters.

In 1992, Alberta implemented a provincial emergency alert system known as the Emergency Public Warning System (EPWS); its development was spurred by an F4 tornado that had hit the Edmonton area on 31 July 1987, killing 27 people. The system was originally operated by the CKUA Radio Network under contract with the province.

Under the 1995 Federal Policy for Emergencies, Industry Canada led the effort for coordinating the provision of an emergency broadcasting service, based on the facilities and services of the Canadian Broadcasting Corporation (CBC), Environment Canada and, as necessary, privately owned networks and stations.