The sustainability of an oil and gas company depends upon its ability to replace reserves at a faster pace than its production rate. The primary determinants of the value of an oil and gas company are its cash flows and earnings, which are dependent upon the quantity and quality of the hydrocarbons it produces, along with commodity sales prices, production potential, which is described by its reserves, reserves replacement rate, and its inventory of capital assets, equipment, infrastructure, and acreage. The purpose of this paper is to establish the relationship between the primary factors that influence value for a cross-section of oil and gas companies for the year ending 2010. We construct regression models for majors and a random sample of North American independents according to production, reserves, technology application, and geographic diversification. We show that reserves and production are strong indicators of market capitalization, and for independents, production and total assets are better proxies of company value than reserves. Multinational independents are valued higher than domestic producers and companies producing primarily from conventional assets exhibit a modest price premium to unconventional producers. We infer the effective capitalization for a sample of private companies and the National Oil Companies of OPEC and compare model-predicted market caps for companies domiciled outside North America.