As the cloud provider is a critical project success factor, Cloud service development requires a different approach than the traditional software development lifecycle. The SaaS Development Lifecycle (SaaSDLC) is an adaptation of the traditional iterative software development process with three additional phases added: Evaluation, Subscribing and Operations. These phases are critical success factors for a SaaS development and deployment due to the external hosting environment. Even if the SaaSDLC described is biased towards ISVs, it is also valid enterprise IT departments that should start looking at themselves as Service Providers and act accordingly.