I consider myself, in the most modest way possible, to fit into the "intelligent layman" group of readers of Science books. I have a moderate to high understanding of high level physics, and can cope with more advanced concepts if they are presented to me in the right way. If this describes you as well, this book will be perfect for you. I have been very interested in the subject of Dark Matter for a while, and I recently decided to research it in a little more detail. Unfortunately, I found that almost all books on the subject fitted into two categories: the pop-sci, which did not go into any detail of the mathematics involved, and talked about just the history behind it, and the high-level journals, which gave me headaches trying to read them. This book is illustrated with many, many helpful diagrams, and is written in a helpful, but not condescending textbook style, which makes handling the more advanced concepts easier. I am surprised that this book hasn't been publicised more- it's, in my opinion, absolutely fantastic. he only other book I enjoyed as much as this one on the topic is John Boslough's "Masters of Time", which now seems to be out of print. By all means, go for this book, and you won't regret it.