The member states of the CEP are the countries of the Wider Caribbean region.

Article 2:1 of the Cartagena Convention defines the Wider Caribbean Region as the "marine environment of the Gulf of Mexico, the Caribbean Sea and the areas of the Atlantic Ocean adjacent thereto, south of 30° north latitude and within 200 nautical miles of the Atlantic coasts of the States". This geographic area stretches from as far north as Florida in the United States to as far south and east as French Guiana on the North Coast of South America. The region also includes Mexico, Central America, and the many small island natios and territories of the insular Caribbean.

The 28 Member States that created the CEP are: