It depends what level you're at. If you're a regular beginner who never lifted anything heavier than a Nintendo control before in his life, and if you have a healthy diet but one without a heap more calories than you need, then the first few months of resistance training won't build much muscle at all.
Like Ricky Ponting has smaller muscles than me, but he can throw the ball faster and further, why? He knows how to exert his strength to best effect. When you begin weight training after being sedentary, it's much the same - you're not really getting more muscles, you're learning to exert your existing strength to best effect.
After those first few months, though... either you add muscle, or you stall in your lifts. So it depends just where you are now, and how far you want to go. To bench your bodyweight you don't have to get bigger unless you're a complete runt now, to bench 150% your bodyweight you'll have to get bigger unless you're pretty hefty now.