This book explains the basics of S-PLUS in a clear style at a level suitable for people with little computing or statistical knowledge. Unlike the S-PLUS manuals, it is not comprehensive, but instead introduces the most important ideas of S-PLUS through the use of many examples. Each chapter also includes a collection of exercises that are accompanied by fully worked-out solutions and detailed comments. The volume is rounded off with practical hints on how efficient work can be performed in S-PLUS. The book is well suited for self-study and as a textbook. The third edition is based on S-PLUS Version 6 for Windows and Unix and has been completely updated. It covers the underlying S Version 4 and the graphical user interfaces for Windows and Unix. A new section of the details of factor objects has been added, Trellis graphs are used in more depth, and new exercises (and solutions) were written. The book serves equally well as an introduction to the R system, and concludes with a comparison of S-PLUS and R.