If you could give a book to your younger self, what would it be?

This book changed my entire outlook on the world.

This is the only self-help book that has helped me.

Definitely. Seriously considered giving this to my younger brother as well...

I took that at face value, and tried to find a manual for how to interact positively with others, and I found H2WF&IP. I treated it like a text book, and it changed my life completely. I was happier, more able to be sociable, and I could get along with people. Now, after a further 30 or more years, I can still see the book's influence as I negotiate deals, manage employees, broker agreements, and generally "do stuff." It's now out-of-date, but if you can make the effort to read it in the context it was written, and to ignore the obvious anachronisms, it's still valuable. The more recent versions try to be more up-to-date, but they lose something as far as I can tell, and I return to the original.

Probably How to Win Friends and influence people.

Another vote for Atlas Shrugged.

Atlas Shrugged - Ayn Rand - Age 17

Atlas Shrugged. I'm not a Rand groupie but seeing some of the core ideas of what I always felt but never could quite articulate literally changed me as a person.

Atlas Shrugged. It would have fired me up to start something.

K&R. I discovered the book at age 17 by myself but that was the book I really wanted when I was 12. Not just because it teaches C -- it teaches the core of the systems programming and design experience. If you're interested in systems development I can't recommend K&R enough.

Ender's Game by OSC

* Ender's Game - Orson Scott Card

The Selfish Gene

I would have given back 'Founders at Work' to my 18 self. I only got to read it once I was 21.

* 1984 - George Orwell

any book in the Discworld series - Terry Pratchett

'The Fountainhead'. It would have assured me that there were many other people with the hacker mindset (which ultimately is what the book is about), it would have helped me prepare for a world where that mindset was not the norm, and hence would probably have avoided years of agony and depression later.

Masters of Doom by David Kushner

Probably "Man's Search for Meaning" by Victor Frankl... Although I'm not sure that the book will have the same impact without the accompanying life events.