Capacity value is the contribution of a power plant to the ability of the power system to meet high demand. As wind power penetration in New England, and worldwide, increases so does the importance of identifying the capacity contribution made by wind power plants. It is critical to accurately characterize the capacity value of these wind power plants and the variability of the capacity value over the long term. This is important in order to avoid the cost of keeping extra power plants operational while still being able to cover the demand for power reliably. This capacity value calculation is particularly interesting because wind power output and demand for electricity are not statistically independent. They are both driven by the weather. This dissertation describes a model of the New England power system in the presence of increasing wind power penetration, used to achieve three major ends: To evaluate the magnitude of the contribution that wind power would make to resource adequacy in the New England Power system at various levels of penetration (up to 50%). To characterize the inter-annual variability in that contribution To assess various capacity value metrics with regard to their ability to predict the long term capacity value of wind power plants, especially based on limited data To characterize the interaction of wind power plants and energy storage with respect to capacity value These ends were achieved by completing three studies: a long-term study based on measured wind data, a high-penetration study based on synthesized data, and an investigation of the effect of grid-scale energy storage. While the methods used in these studies are generally applicable, New England is used as a consistent example since many of these phenomena are strongly affected by the regional wind and power system characteristics. The results of this work show that wind power capacity value is relatively high at low penetration and decreases substantially as penetration increases to 50% and that this is not significantly improved by the inclusion of grid-scale (daily load-shifting) energy storage. Also, the capacity value of this energy storage, considered separately is relatively high, and not strongly dependent on wind energy penetration level. In future power systems with higher wind penetrations than 50% or those relying on longer-term storage (which could be necessary to reach very high levels of renewable penetration), new metrics of capacity value may be necessary to ensure system adequacy