From publisher blurb:
EVERYTHING THEY DO IS MAGIC!
Secrets of the Witchkind presents everything you need to bring a new, highly magical player character race to at d20 System campagin setting you enjoy. The Witchkind aren't just spellcasters... everything they are is tied to magic, and they use it more naturally than any other beings in the multiverse. Get to know them and play them with this OGL supplement for d20 Miodern (but easily adaptable to any d20 System game) that contains rules for creating Witchkind player characters, details on their unique spellcasting methods, and 17 feats and 6 talent trees to augment and expand their magical abilities.
Like Secrets of the Immortals, this product was inspired by and loosely based on a classic television series. If you've ever thought the story of an average guy who marries a witch and has to deal with the culture shock that is her family, this book is the perfect starting point. It's also the perfect tool if you want to bring a looser spellcasting system that more resembles those found in books and movies to the d20 System.