This is for Text Centering (which is what the question was about)
For other types of content, see Flavien’s answer.
Update: Bootstrap 2.3.0+ Answer
The original answer was for an early version of bootstrap. As of bootstrap 2.3.0, you can simply give the div the class .text-center
.
Original Answer (pre 2.3.0)
You need to define one of the two classes, row
or span12
with a text-align: center
. See http://jsfiddle.net/xKSUH/ or http://jsfiddle.net/xKSUH/1/