how to check package status

hello all, i'm looking for a way from the command line to see if a certain package is installed or not. apt-cache seems to list a lot of information sans the single boolean info i need ^__^

so far the closest i've come is to do apt-get -s to simulate an install and see if anything would be done, but it's clumsy... there must be a better cleaner way

thanks

dpkg -l | grep packagename

that does it, thanks ^__^

Or:

apt-cache policy [package-name]

the simplest one...

dpkg -s packageName