Misconceptions high school students have about constructs in the BASIC programming language were examined in this study. A total of 96 high school students received a screening test after a semester course in BASIC programming, and 56 of these students were subsequently interviewed by means of questions and short programs prepared in advance. The purpose of the screening test was to detect possible problems with constructs such as reading data, branching, and looping. Tape recordings, written notes, and responses generated during the interviews were used to determine patterns of errors and misconceptions. Notations of frequently, fairly frequently, and occasional were given to the students' error rate. The most common errors were: (1) reversal of assignment statement; (2) misinterpretation of quotation marks; (3) difficulties with READ statements; (4) loop construction; and (5) IF statement utilization. Examples of the most common errors are included to illustrate each misconception together with student remarks as to why the error occurred. A summary assessment of students interviewed concludes the report. (JB)