Nine experienced users of electronic spreadsheets each created three spreadsheets. Although participants were quite confident that their spreadsheets were accurate, 44 percent of the spreadsheets contained user-generated programming errors. With regard to the spreadsheet creation process, we found that experienced spreadsheet users spend a large percentage of their time using the cursor keys, primarily for the purpose of moving the cursor around the spreadsheet. Users did not spend a lot of time planning before launching into spreadsheet creation, nor did they spend much time in a separate, systematic debugging stage. Participants spent 21 percent of their time pausing, presumably reading and/or thinking, prior to the initial keystrokes of spreadsheet creation episodes. © 1987, ACM. All rights reserved.