Abstract: Groups of consenting users such as families can track where other members of the same group are under agreed upon access arrangements. The locating system can operate in a passive mode. Users do not have to actively sign-in or check-in to the locating system for the locating system to obtain individual location determination estimates. The locating system collects communications device usage information from a plurality of communications networks, e.g., landline, cellular, Wi-Fi, DSL. The locations of communication devices and infrastructure are known. Members of locating groups are associated with various communication devices detected are being used. Approximate locations of an individual member or members of a locating group are inferred from detected device usage information. A location report is generated, e.g., in a map, table, or audio format, indicating the determined location of individuals, and optionally including time tags. The report is provided to authorized members of the locating group.