There is a wealth of theoretical knowledge about the developmental abilities and skills of children. However, this knowledge is not readily accessible to designers of interactive products. In this paper, we present the requirements, design and evaluation of developmentally situated design (DSD) cards. DSD cards are a design tool that makes age specific information about children’s developing cognitive, physical, social, and emotional abilities readily accessible for designers. Initial requirements were elicited through interviews with design practitioners and students. The cards were evaluated through a design-in-use study in which design students used the cards to address three different design problems. Our analysis of observational notes and post-design interviews revealed how the cards’ characteristics enabled different kinds of uses including framing, orienting, inspiring, informing, integrating and constraining. We conclude with a discussion of possible refinements and an an...