Systems of computer mathematics find more and more broad application in a number of natural, economical and social fields. These systems are rather important tools for scientists, teachers, researchers and engineers, very well combining symbolical methods with advanced computing methods. One of leaders among means of this class undoubtedly is the Mathematica system. The book focuses on one important aspect - modular programming supported by Mathematica. The given aspect is of particular importance not only for appendices but also above all it is quite important in the creation of the user means that expand the most frequently used standard means of the system and/or eliminate its shortcomings, or complement the new facilities.Software tools presented in the book contain a number of rather useful and effective methods of procedural and functional programming in Mathematica system that extend the system software and allow sometimes much more efficiently and easily to program the objects for various purposes first of all wearing system character. The above software tools rather essentially dilate the Mathematica functionality and can be useful enough for programming of many applications above all of system character. Furthermore, the book is provided with freeware package AVZ_Package containing more than 720 procedures, functions, global variables and other program objects.The present book is oriented on a wide enough range of users of systems of the computer mathematics, teachers and students of universities at courses of computer science, mathematics and other natural-science disciplines.In the course of preparation of the present book the license releases 8 � 10 of the Mathematica system provided by Wolfram Research Inc. have been used.