During the past fifteen years, several new atypical antipsychotic medications suitable for the treatment of symptoms in schizophrenia entered the marketplace. In the process of drug development, the sponsoring pharmaceutical manufacturers designed and implemented multiple major clinical studies demonstrating efficacy for each of the new agents. The design and implementation of these sponsored preapproval clinical studies were intimately linked with the prerequsite to comply with regulatory requirements for approval of a new atypical agent. The conditions for approval motivate the pharmaceutical industry to perform efficacy studies using the same trial design elements, and uniform data analytic approaches for the evaluations. This presentation, using the FDA's Summary Basis of Approval database, will overview established practice of providing evidence to regulatory authorities about the claimed properties of new pharmaceutical products with regard to antipsychotic efficacy. The overall designs including the timing of evaluations, psychometric rating scales used for evaluations, and the use of both measured and derived outcome variables as well as other principal characteristics of the trials, such as the choice of population for efficacy analyses, and methods of handling missing data will be reviewed. The established conventions and procedures will be contrasted with scientific concepts and principles and practical utility.