ISO-New England (ISO-NE) and seven of its transmission owners have installed phasor measurement units (PMUs) and phasor data concentrators (PDCs) across the six states in the New England control area. These devices, in conjunction with a set of new applications, have the potential to improve the reliability of the transmission grid and to prevent the spread of local disturbances to neighboring regions through enhanced monitoring capabilities and increased situational awareness. ISO-NE is exploring a long-term plan for operations where advanced transmission management software will assist in determining real-time grid stability margins. ISO-NE has already used this technology to increase power system engineers visibility into bulk power system conditions in near-real time and enabled the potential for earlier detection of disturbances that could result in instabilities or cascading outages. Access to more granular grid state information has allowed ISO-NE power system engineers to improve power system models and analytical techniques, enhancing the overall reliability of the ISO-NE system.