This paper proposes a model to value a phased rollout, and to determine the optimal time of a phased rollout as well as the optimal rollout area. Since a phased rollout of new products can be considered as an option on a worldwide launch, real option theory is applied to enhance decision making about entry strategy. We derive the analytical properties and illustrate the model with a case on phasing the rollout of CD-I at Philips Electronics. Under the assumptions made, we found that the value of a phased rollout strategy mainly depends on market and technology uncertainty and the expected net present value of the investment. The maximum value of phasing the rollout of CD-I was nearly 23% of the investment cost.