The nature of novice programmers' mental models for BASIC statements following preliminary BASIC instruction was assessed with 30 undergraduates who were taught BASIC through a self-paced, mastery manual and who were simultaneously given hands-on access to an Apple II microcomputer. Following instruction, the students were tested to determine their conceptions of what goes on inside the computer during the execution of each of nine BASIC statements: (1) LET A = B + 1; (2) PRINT C; (3) LET D = O; (4) PRINT "C"; (5) IF A IS LESS THAN B GOTO 99; (6) INPUT A; (7) 20 DATA 80, 90, 99; (8) 30 READ A; and (9) 60 GOTO 30. Data gathering instruments included a questionnaire to obtain information on the subject's demographic characteristics and background in mathematics and/or computer programming; the IBM Programmer Aptitude Test; and both verbal and visual (diagram) tests on the nine statements. Results showed that despite adequate performance on program generation mastery tests, students possessed a wide range of misconceptions concerning the statements they had learned. This paper presents a catalog of the subjects' mental models for each of the statements, frequency tables showing incorrect or incomplete transactions produced for each statements, and a six-item reference list. Appendices include instructions, a sample page, and a sample protocol from each of the two tests on the BASIC statements. (Author/LMM)