How do I enable automatic capitalization in OS X?

Can I turn on automatic capitalization on my iMac running OS X 10.9, Mavericks? It is selectable in iOS on my iPad but I can't find a similar switch in Mavericks.

You can use a third party such as TextExpander ($35) for this. Paired with the right third party dictionary (TidBITS Autocorrect Dictionary), which is downloadable from within TextExpander, it corrects most of my typos that Mac OS X misses, as well as providing shortcuts for frequently typed snippets.

Using TextExpander just for sentence capitalization is a bit of overkill, but if you embrace it, you wind up with an excellent tool that you can easily adapt to your needs.

It's not available yet on Mavericks as such. You can ask Apple to add it via

http://www.apple.com/feedback

Some apps might have it internally (but Pages 5 does not, only Pages 4).