This book was originally written to support an introductory course in Object Orientation through the medium of Smalltalk (and VisualWorks in particular). However, it can be used as a book to teach the reader Smalltalk, to introduce object orientation as well as present object oriented design and analysis. It takes as its basic premise that most Computer Scientists I Software Engineers learn best by doing rather than from theoretical notes. The chapters therefore attempt to introduce concepts by getting you the reader to do things, rather than by extensive theoretical discussions. This means that these chapters take a hands-on approach to the subject and assume that the student/reader has a suitable Small talk environment available to them. The chapters are listed below and are divided into six parts. The reader is advised to work through Parts 1 and 3 thoroughly in order to gain a detailed understanding of object orientation. Part 2 then provides an introduction to the Smalltalk environment and language. Other chapters may then be dipped into as required. For example, if the reader wishes to hone their Smalltalk skills then the chapters in Part 4 would be useful. However, if at that point they wish to get on and discover the delights of graphical user interfaces in Smalltalk, then Part 5 could be read next. Part 6 presents some more advances subjects such as metaclasses and concurrency which are not required for straight forward Small talk development.