The OECD Competition Committee debated energy security and competition policy in February 2007. This roundtable examined the links between competition policy and energy security, with a focus on natural gas. The discussion began by addressing the questions of the meaning and importance of energy security; and the determinants of energy security, particularly as they relate to competition policy. It continued in dealing with gas supply, transportation, and distribution, addressing five aspects that relate to different aspects of energy security: (1) the role of substitutes for natural gas in fostering competitive gas supply; the role of regulation in promoting or inhibiting infrastructure investment; (2) how to promote an adequate level of infrastructure investment; (3) the role of unbundling in fostering competition and promoting energy security; (4) the role of storage capacity in system efficiency and buyer bargaining position; (5) and the determinants of entry into merchant sales of natural gas.