A study examined text-based scientific concepts and described how those concepts were elaborated in three high school biology textbooks. The three textbooks were aimed at different student audiences: non-college bound students, special education students, and high school students at all levels. A concept analysis was established for each text, and then the extent to which the concepts were elaborated was determined. Results indicated that the textbook designed for the least able students presented the least amount of information. Results also indicated that the other texts presented similar amounts of information and elaborated many of the concepts, but to different degrees. (Three figures and two tables of data are included; 40 references are attached.) (RS)