SUMMARY: Evidence-centered design (ECD) is an assessment development methodology which explicitly clarifies what an assessment measures and supports skills interpretations based on test scores. This paper describes the ECD processes used to develop the TOEIC Speaking and Writing tests. Evidence collected through the test design process produced foundational support for the validity of TOEIC Speaking and Writing test score interpretations. ABSTRACT: This paper describes the evidence-centered design (ECD) processes used to create a final design process for the TOEIC Speaking and Writing tests. The design process was used to produce task specifications and a test blueprint that would ultimately support the generalization of test scores from any individual set of test tasks to performance on actual tasks required in the workplace. This paper is part of the Research Foundation for TOEIC: A Compendium of Studies, published by ETS in 2010.