Effective strategies for service-oriented architecture (SOA) and application programming interfaces (APIs) require maturity on multiple fronts. Application development teams and solution architects are challenged to draw a clear relationship between SOA and APIs, and it's even more challenging to craft a strategy for obtaining the highest business value from both. A maturity model's flexible framework of related best practices guides delivery organizations' incremental improvement today while they evolve toward coherent long-term best practices. This report describes Forrester's model of eight central maturity areas — ranging from portfolio management and design strategies to development life cycles and funding — as a foundation for technology leaders to evolve their organizations' SOA and API strategies toward greater business agility and value for money.