The notion of validity encapsulates the echo of the physical within the technical. The technical force of a language course, test or plan needs to be evaluated for its effects. On the norm side, this yields a design principle that asks whether the design is adequate, and can be validated. That kind of technical validation is perhaps most prominent in language assessment. This quality enhancing process can productively be extended to the other interventions. On the factual side, the operation of subjective technical processes which produce technical objects come into focus, as well as factual technical changes caused by interventions. [For the complete volume, "A Theory of Applied Linguistics: ?magining and Disclosing the Meaning of Design. Educational Linguistics. Volume 65," see ED672528.]