Finding psychological tests and scales is a two-part process - identify what tests exist that would be useful to you, and then see what it will take to get the actual "instrument".
Many instruments are proprietary, meaning that you have to pay for them. But there are many that are developed and provided for free by academic scholars. Some of these are actually embedded in journal articles describing their development, while others may be available upon request by just emailing the first or "corresponding" author of the article.
Commercially available (proprietary):
- Mental Measurements Yearbook (series of print volumes) - latest edition (21st, 2021) is on Reserves, Z5814.P8B932. Each edition describes different tests, so look through several volumes.
- Tests in Print (series of print volumes) - Reference Z5814.E9T47.
- Tests (series of print volumes) - Reference BF176.T43 2003 (for older tests)
- Test Reviews Online (Buros) - basic keyword search to find commercially available tests - note that this search leads you to purchase a *review*, not the actual test. Use it just to identify relevant tests, not purchase them.
- ETS Test Collection - over 25,000 tests indexed, only about 1,200 of them available freely online through this database, but can provide useful information about what exists and contact information to purchase it. The results reference physical copies in their library, but we don't have access to those directly, so use this to identify tests on your topic then use PsycINFO (or ERIC if it's education-related) to see if you can get it for free via a published article or by contacting the author.
Academically available (perhaps, see explanation below):
Search PsycINFO, using a combination of the search terms (put this on one line of the search screen): SU "test validity" OR ZK "tests & testing"
along with the keywords for the topic of the scale you want to find in the other lines.
This finds articles about tests, and often the article that is about the validity of the test, especially the oldest one about that test, includes either the test itself (possibly as an appendix) or at least contact information for the author of the test.
If the researchers who created the test/scale have not "monetized" it, they are often willing to just send it to you via email upon request. You want to make sure you've checked all of their articles first (including appendices and "supplementary material" the publisher provides on their website for the article) and lay out your own scholarly credentials (e.g. you're a doctoral student working on a dissertation on topic X) in the email asking them for a copy of the scale and scoring system.
Depending on your topic, other databases that may have useful articles reporting on new scales that you might be able to get a copy of include:
- Medline - use this in the first search box then add your keywords in the others: (SU "surveys and questionnaires" OR SU psychometrics) AND validity
- SocIndex - use in the first search box: (DE "PSYCHOLOGICAL tests" OR psychometrics) AND (validity OR reliability)
- ERIC (education-related, K-12 and higher ed) - use in the first search box: (SU "Psychological Testing" OR SU "Psychometrics") AND ("test format" OR "test validity")