Psychometric practice does not always converge with the advances of psychometric theory. In order to investigate this gap, the authors focus on the 10 most used psychological tests in Europe, as identified by recent surveys. The article analyzes test manuals published in 6 different European countries for these 10 most used tests. A total of 32 test manuals (11 for cognitive ability tests, 7 for personality measures, and 14 for clinical measures) are analyzed in terms of their congruence with the latest precepts of the Joint Standards for Educational and Psychological Testing and the Guidelines of the International Test Commission. These two documents are seen as reflecting the latest accomplishments in psychometric theory and as sound recommendations of best psychometric practice. Issues related to reliability; measurement error; consistency as related to a measurement model, validity, validation procedure, scales, norms, and score comparison; and test adaptation are analyzed for each test manual. The data show a gap between psychometric practice and psychometric theory. The authors try to explain the reasons for this gap and suggest ways of closing this gap in the future. (Contains 3 tables and 2 figures.)