Understanding the characteristics of radicals formed from silicon‐containing heavy analogues of alkenes is of great importance for their application in radical polymerization. Bulky and electronic substituent effects in such compounds as phosphasilenes not only stabilize the Si=P double bond, but also influence the structure and species of the formed radicals. Herein we report our first investigations of radicals derived from phosphasilenes with Mes (2,4,6‐trimethylphenyl), Tip (2,4,6‐triisopropylphenyl),...