Types of Project Life Cycles

The PMBOK Guide – the cornerstone of the Project Management Professional (PMP) certification offered by the Project Management Institute (PMI) – defines the project life cycle in terms of phases. While the phases are usually executed sequentially, there can also be some overlap of activities from phase to phase:

  • Initiation: Develop the project charter and identify stakeholders.
  • Planning: Develop the project management plan.
  • Execution: Design and build the product or service.
  • Monitoring and controlling: These activities go on throughout the project.
  • Closing: Hand off the product or service for delivery, and the project is closed.

Using a Project Life Cycle model helps teams focus on the required deliverables to complete a project and provides a method for gaining better control over the project. There’s no “one size fits all” approach to life cycle management. The chosen model or approach depends on multiple factors, including an advance understanding of the project scope and the desired or necessary level of customer involvement throughout the process.


With the Predictive life cycle, the project team runs through each project phase just once, linearly. They don’t move to the next phase until completing all tasks of the current one. This approach requires extensive upfront planning to be sure all process steps are well-defined and understood.

The Predictive approach works well when the three primary project constraints – schedule, cost, and scope – are articulated and agreed upon ahead of time at both high and detailed levels.

The Iterative and Incremental Life Cycles

Although the Iterative and Incremental life cycles also have five phases, there’s no limit to the number of times each phase may be entered. Instead of a linear progression, phases are revisited as needed. These approaches may be helpful for projects with unpredictable scope. And when the highest priority is achieving exactly what the client wants or the best possible product or service, returning to previous phases may be required.

While upfront planning is helpful for any project, those using these approaches must accept that detailed planning and plan refinement will occur throughout the project. This is especially true when customer feedback comes throughout the project, influencing the project’s direction.

The Agile Life Cycle

The Agile life cycle is a hybrid of the other models. Typically the Initiation and Closing phases happen only once. The Planning, Execution, and Monitoring/Controlling phases may occur iteratively as often as required to get the desired result. Results at the end of the Monitoring/Controlling phase are often presented to the customer for feedback. This feedback then determines what happens in the next incremental run-through. Once the customer has given final approval and is satisfied with the result, the Closing phase can be completed.

This approach can be used in areas or projects where rapid scope adjustment is required, including iterations occurring in parallel. As with the Iterative and Incremental methods, detailed scope requirements may only be finalized ahead of the next iteration or phase, at the point customer feedback is incorporated.

Summary of similarities and differences

All approaches have the following in common:

  • High-level planning is required at the beginning of the project.
  • A high-level scope definition is required at the beginning of the project.

Differences include the following:

  • Detailed scope is well-understood at the beginning of Predictive projects. However, detailed scope is finalized at the start of each phase or iteration for the other models.
  • The choice of when to use each life cycle type varies:
    • The Predictive model is best for projects that are well-understood from the outset.
    • The Iterative and Incremental models work well for large or complex projects.
    • The Agile model can be most applicable for projects where the scope is not well-understood from the start, or where the environment is rapidly changing.
  • Customer involvement is focused on the beginning of Predictive projects. Customer involvement may be periodic throughout the project for Iterative and Incremental projects. For Agile projects, customer involvement is continuous.


At Thurman Co., we recognize that project management is more than just wrangling a schedule and budget; a full suite of skills goes into effectively managing projects.

We help businesses manage projects to significantly impact their success and growth. When you’re ready to put your project in the hands of a trusted professional organization, contact us to learn more about working together.

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