Based on our experience with dilute magnetic semiconductors, we use density-functional calculations to do a systematic theoretical research of new materials combining semiconducting and magnetic properties. We were the first to show theoretically that I-Mn-V compounds are semiconductors with a stable antiferromagnetic arrangement of Mn local magnetic moments while the corresponding diluted systems I-(II,Mn)-V can be turned into a ferromagnetic state at sufficiently high concentration of carriers. We plan to continue a detailed theoretical investigation of the atomic and electronic structure as well as magnetic properties of these and related materials with a potential spintronics application.