An Exclusive Provider Organization (EPO) insurance plan is a network of individual medical care providers, or groups of medical care providers, who have entered into written agreements with an insurer to provide health insurance to subscribers. Basically, an EPO is a much smaller PPO. With an EPO you won't be required to get a referral before seeing a specialist. This makes it easier to see a specialist since you’re making the decision yourself, but you need to be very careful that you’re seeing only specialists that are in-network with your EPO.