Removing a wall to enlarge a room

I would like to open up my living room, by removing a wall. How can I tell if I can safely do this.

The first thing you want to do is determine if it is a load bearing wall - that is if it is supporting a floor, ceiling or roof in some way.  The easiest way to do this is to get above the wall if there is attic space and see if the ceiling rafters or roof supports are in any way resting on the wall.  If you can't get above the wall because it has living space above it then you may have to cut into the ceiling on either side to see if the joists rest on the wall.  Sometimes you can look at the direction of the floor joists that the wall that is to be removed is sitting on.  If the joists run parallel to the wall, then there is a good chance that the wall may be non-bearing.  If the wall is non-bearing, then you should be able to open it up with out too much problem.  If the wall is bearing, then you should consult a structural engineer to properly size a replacement beam for the removed wall section.  Also, be certain to temporarily support the load above while you are removing the wall. 

Secondly, thoroughly inspect the area below and above the wall to determine if you have any type of pipes, ducts or wires running the wall.  You want to make certain that these can be relocated before proceeding with the wall removal.  Good luck and good remodeling.