The five maturity levels, each a layer in the foundation for ongoing process improvement, are designated by the numbers 1 through 5:
1. Initial
2. Managed
3. Defined
4. Quantitatively Managed
5. Optimizing
Remember that maturity levels 2 and 3 use the same terms as capability levels 2 and 3. This consistency of terminology was intentional because the concepts of maturity levels and capability levels are complementary. Maturity levels are used to characterize organizational improvement relative to a set of process areas, and capability levels characterize organizational improvement relative to an individual process area.