Spreadsheets are among the most widely used end- user programming systems. Unfortunately, there is a high incidence of errors in end-user spreadsheets, and some of these errors have high impact. In this book, we describe techniques we have developed to help end users develop safer spreadsheets. As part of our research, we have examined typical software development activities like programming, testing, and debugging from an end-user software engineering perspective, and developed approaches to support them better. These include techniques for (1) prevention of reference, range, and type errors by generating spreadsheets from user-defined templates, (2) detection of unit errors by carrying out automatic consistency checking of spreadsheet formulas using labels within spreadsheets, (3) detection of faults within spreadsheets by helping end users test better using constraint- based automatic test-case generation, and (4) correction of identified faults within spreadsheet formulas using a spreadsheet debugger that exploits the user's expectations about the output of their spreadsheets.