#1 for me would be The Intelligent Investor, by Benjamin Graham. Also read all of Warren Buffett's Letters from the Chairman - they're all up on the Berkshire Hathaway website. Peter Lynch's books are good too.
I see a lot of people here recommending A Random Walk Down Wall Street, which is a good book, but you're going to finish it and say "This investing stuff is too complicated for me. I think I'll just put my money in index funds." Which is perfectly sensible investment advice, but if that's all you want, I can tell you "Go invest in index funds" right now and save you a couple hours of reading. ;-)
Jeremy Siegel's Stocks for the Long Run is like Random Walk - it's decent, but the conclusion is basically "go invest in a stock index fund and don't worry about it". I'm not even sure that's great advice right now - he bases a lot of his argument on historical performance, but when an asset class has done well over the recent past, that usually means it'll do poorly in the near future. Read neither or both - Random Walk gives you good perspective for understanding Stocks for the Long Run.
Finally, if you do get into investing, make sure you start small. I've made some wonderful investment decisions and some truly terrible ones. The wonderful ones more than compensated, but they looked very similar at the time, and if I'd put all my money into the terrible one there wouldn't be any capital available for the wonderful one.
Actually, I'd recommend doing some dry-runs: pretend that you're putting money in a stock, and then track how well you'd have done over time if it were real. Read all the 10-Ks for the stock (they're up in the EDGAR database at the SEC's website), research all the fundamentals, and listen to the analyst conference calls (Yahoo Finance webcasts them live whenever earnings come out). That'll give you a sense of what questions to ask and what events affect the stock price.
I did some of those dry runs and lost hypothetical money on a lot of them, which makes me very glad that they're just dry runs. ;-)
Dry runs aren't terribly useful, unless you're backtesting
- investing well means dealing with fear and greed, and you can't simulate that. You need skin in the game.
I see a lot of people here recommending A Random Walk Down Wall Street, which is a good book, but you're going to finish it and say "This investing stuff is too complicated for me. I think I'll just put my money in index funds." Which is perfectly sensible investment advice, but if that's all you want, I can tell you "Go invest in index funds" right now and save you a couple hours of reading. ;-)
Jeremy Siegel's Stocks for the Long Run is like Random Walk - it's decent, but the conclusion is basically "go invest in a stock index fund and don't worry about it". I'm not even sure that's great advice right now - he bases a lot of his argument on historical performance, but when an asset class has done well over the recent past, that usually means it'll do poorly in the near future. Read neither or both - Random Walk gives you good perspective for understanding Stocks for the Long Run.
Finally, if you do get into investing, make sure you start small. I've made some wonderful investment decisions and some truly terrible ones. The wonderful ones more than compensated, but they looked very similar at the time, and if I'd put all my money into the terrible one there wouldn't be any capital available for the wonderful one.
Actually, I'd recommend doing some dry-runs: pretend that you're putting money in a stock, and then track how well you'd have done over time if it were real. Read all the 10-Ks for the stock (they're up in the EDGAR database at the SEC's website), research all the fundamentals, and listen to the analyst conference calls (Yahoo Finance webcasts them live whenever earnings come out). That'll give you a sense of what questions to ask and what events affect the stock price.
I did some of those dry runs and lost hypothetical money on a lot of them, which makes me very glad that they're just dry runs. ;-)