This study identified students' conceptual difficulties in understanding concepts and processes associated with cell water relationships (osmosis), determined possible reasons for these difficulties, and pilot-tested instruments and research strategies for a large scale comprehensive study. Research strategies used included content analysis of commonly used textbooks, three paper-pencil questionnaires featuring 72 true/false items, and individual interviews based on two demonstration experiments. One hunderd forty-two students in grades 9, 10, and 11 served as subjects. Among the findings are those indicating that: (1) serious misconceptions exist among high school students and student teachers with regard to basic concepts such as solutions, solubility, particulate nature of matter, and molecular movement, and these misconceptions may well be among the reasons for difficulties in understanding osmosis and osmotic relationships; (2) students use textbook definitions of osmosis and diffusion without fully understanding the concepts; (3) teleology and anthropomorphism are widely used among students, as they provide causal explanations; (4) certain textbooks (such as the Biological Sciences Curriculum Study textbooks) hardly mention osmosis; (5) the terms water potential, osmotic potential, osmotic pressure, and hemolysis are rarely dealt with in high schools; and (6) the research instruments and strategies appear to be adequate and effective. (JN)