Co-author: I. Bogomolov. This paper is focused on qualitative software characteristics, what determines software quality and methods to ensure and improve it. In the research the problem was investigated from two points of view: software development and project management. Concerning software development, was formulated what properties have qualitative software and compile the best practices to ensure and improve these properties and overall software quality. Concerning project management, current theory was analysed and found another value – development team, which significantly influences quality. Also, dependency between team productivity and number of team members was stated.