This review of the literature focused on three decades of research related to precollege student understandings about the nature of science. Various interpretations of what aspects characterize the nature of science were examined, revealing an agreement among scientists, science educators, and those involved in policy-making arenas that the nature of science is multifaceted and an important component of scientific literacy. A summary of the research regarding the adequacies of student conceptions about the nature of science revealed inconsistent results. Although the majority of studies show that student understandings are less than desirable, there is research that indicates that student conceptions are acceptable. Research on the impact of instructional materials and techniques on student understandings was also reviewed. The effects of language in science instruction, the content emphasis of instructional materials, integrated science curricula, and instruction in general were curricular variables found to have a negative impact on student understandings about the nature of science. Empirical evidence about the success of innovative instructional materials and techniques designed to facilitate more adequate understandings of the nature of science is needed.