Polyvinylsilazane, as a precursor for Si-C-N ceramics, was prepared by ammonolysis of functionalized chlorosilanes. Pyrolysis under inert atmospheres at T-P = 1000degreesC led to an amorphous Si-C-N-(H) ceramic. Further heat treatment caused the transformation to the thermodynamically stable crystalline phase assemblage. The structural changes, especially those of the excess carbon, were studied by characterizing the solid intermediates via solid-state magic angle spinning nuclear magnetic resonance spectroscopy. Moreover, Raman spectroscopy, electron spin resonance spectroscopy, and chemical analysis were used. Based on these methods, a comprehensive picture of the formation and behavior of the free-carbon phase present in polymer-derived ceramics was obtained.