This is an introduction for students who want to start constructing prototype applications in Smalltalk-80, but who don't want a detailed guide to the implementation. Requiring no previous exposure to Smalltalk-80 or object-oriented programming in general, the text offers a tutorial approach, with a large number of short chapters, each covering specific points. It mixes the language syntax, the class hierarchy and the user interface to maximize student interest and to stress relationships between them, and uses cross-referencing and indexing so that students can find what they are looking for. The book also provides a large number of illustrations of Smalltalk-80 operation, and contains extensive original exercises of various degrees of complexity at the end of most sections.