I'm not sure how many people have read Margot Adler's Drawing Down the Moon but I would say that it's a good start to understanding the origins of Neo-Paganism and Neo-Wicca. I'm not going to lie; it is not a short and easy read. It's a scholarly text that's full of wonderful insight into how Paganism and Wicca has involved into what it is today.
I must admit, however, that a lot of the interviews that were collected for this book occurred throughout the 70s when Paganism and Wicca were just starting to really develop. It has lovely background information on Gerald Gardner who is often accredited with founding modern Wicca. I use the word "modern" loosely because his teachings are supposedly based off a much more ancient tradition.
It's a very thought provoking book which will definitely get you wondering about how and why you chose to follow this spiritual path. I suggest anyone who is thinking about following the Pagan or Wiccan Path to please read this book first. It'll help you in understanding your choices and understanding the true nature of Paganism/Wicca, how it was developed, why is was developed, and what is expected from you.
There are quite a few sections in the book that explains different sects of Wicca and Paganism, feminism, sexual orientation, rituals, and more. This book is not a pleasure read, but for those who are looking up serious information on these spiritual paths and/or wish to gain knowledge on their own tradition. I would suggest that anyone who wants to read this book to keep in mind that the book is based off a lot of information that was available in the 70s and to keep in mind the context from which the interviews were conducted. Also, bear in mind the availability of books about the Craft that were available to the public around this time frame which weren't very many.
All in all, this book is for anyone who is seeking to learn more about their traditions or are looking into following the Pagan/Wiccan Path. Plus, the newest edition just came out for it!