This paper discusses the types of readiness that are necessary for learning in science and how to assess them. Subject matter readiness refers to what students bring in terms of facts, concepts, generalizations, and principles to the new science lesson. Evaluating many aspects of student background, such as prior instruction, helps in the evaluation of this aspect of readiness. Attitudinal readiness is another important type. Good attitudes toward the curriculum help the student achieve the objectives of the curriculum. Instructional readiness refers to the preparation of the student and the level of complexity of the curriculum. Students also need maturational readiness, with development appropriate to the material being taught. Contextual readiness refers to students' perceptions of ways of using what has been learned in science. All of these types of readiness are necessary for optimum learning. Some suggestions are given for assessing each of these forms of readiness. (Contains 11 references.) (SLD)