Identifying load bearing walls doesn't always require an expert, but it does require keen observational skills. If you plan on making any modifications to your home, you have to first identify which walls support structural loads. Attempting to remove, or even alter, a load bearing wall without first providing temporary support, and then building in dew support, could be disastrous.
Load Bearing Walls
All the outside walls of your home are considered load bearing. The weight of the roof is born by these walls. Interior load bearing walls can be trickier to identify. Go into the basement (if your home has one) and look for support posts or girders and also beams running the length of the basement. Walls above these structures are most likely load bearing. Also, walls that run perpendicular to the direction of the floor joists will be load bearing.
If you feel you need a professional opinion, hire a contractor or building inspector to tell you which walls are load bearing. You must be absolutely sure which walls bear the weight of the house before attempting any remodel. You can usually discern which walls by carefully observing support features and by determining the walls that run perpendicular to the joists.
Now that you can knock down that wall, here's how to turn two small rooms into one large one.