Concern about passing those examinees who should pass, and retaining those who need remedial work, is one problem related to criterion-referenced testing. This paper deals with one aspect of that problem. When determining how many items to include on a criterion-referenced test, practitioners must resolve various non-statistical issues before a particular solution can be applied. A fundamental problem is deciding which of three true scores should be used. The first is based on the probability that an examinee is correct on a "typical" test item. The second is the probability of having acquired a typical skill among a domain of skills, and the third is based on latent trait models. Once a particular true score is settled upon, there are several perspectives that might be used to determine test length. These solutions are reviewed and critiqued. Some new results are described that apply when latent structure models are used to estimate an examinee's true score. (Author/GK)