This paper reviews what is known about intelligence and the use of intelligence tests. Environmental and hereditary factors that affect performance on intelligence tests are reviewed, along with various theories that have been proposed about the basis of intelligence. Intelligence tests do not test intelligence per se but make inferences about a person's intelligence. Intelligence tests contain some measurement errors, and no single intelligence quotient (IQ) test or theory is uniformly accepted as the "best." It is suggested that the best way to test intelligence is to use a reliable battery of tests or combination of tests with many subcategories. These subcategories should reflect a wide range of abilities, processes, and contexts. In addition, the results of tests should be reported in a clear and analytical way. These reports should guide teachers and parents in helping each individual student in the most appropriate way. (Contains 3 figures, 3 tables, and 30 references.) (SLD)