This introduction has been designed to teach Mathematica as a programming language to scientists, engineers, mathematicians and computer scientists. The text may be used in a first or second course on programming at the undergraduate level or in a Mathematica-related course in engineering, mathematics or the sciences. It is also intended for individual study by students and professionals. The text does not assume familiarity with Mathematica, nor does it require prior programming experience. The book and diskette contain over 200 exercises drawn from many areas of science, engineering, mathematics and computer science.