This book is an introduction to IBM High Level Assembly language (HLASM) programming. It's based on the author's forty years of experience teaching IBM Assembly language to thousands of university students and professional programmers at Fortune 500 companies. In twelve chapters, the book covers the fundamental topics needed by a beginning assembler programmer to start working professionally. The author believes that the best way to become proficient with this language is to write interesting programs that exercise your knowledge of fundamental HLASM concepts. The book contains eighteen programming assignments that will build your proficiency and your confidence as an assembler programmer.