Just as objectivist theories have provided foundations for traditional tests, constructivist theories can offer foundations for performance assessment design and development methods. The tenets and principles embedded in various learning theories provide a solid foundation that can be combined with psychometric principles to help assessment developers make consistent, well-founded design and development decisions. Success in using these foundations depends upon understanding the linkages from theory to practice. This article is Part 1 of a two-part series. The theoretical foundations discussed here provide a set of general principles for how to go about defining domains and assessment programs. These foundational principles easily and smoothly connect with various psychometric principles. Part 2 of this series, which will appear in the next issue of "TechTrends," will discuss principles for specifying individual performance tasks. Together, the two parts of this article offer a first attempt at explicitly defining a set of performance assessment design principles. At least two important subsequent steps should be evident at this point for the long term. First, these and other performance assessment design principles need to be researched, tested, revised, and eventually codified into standards of best practice. Second, psychometric theory and practice needs to build means for dealing with large-scale, standardized performance assessment--perhaps following a similar path. (Contains 2 figures, 3 footnotes, and 15 recommended readings.)