Unfortunately, there is no "one stop shop" for finding tests and measurements, and oftentimes if the test is published, it is not free. This guide provides some resources and tips for how to find, modify, or use tests and measurements.
Published tests and measurements are copyright protected and must be purchased from the publisher. Indexes of publishers can be found in the Mental Measurements Yearbook with Tests in Print. If you plan to use an unpublished test, you should contact and obtain permission from the author of the test.