The ability to add a sim depends on the following: 1. Your town's sim count - You are only allowed a certain number of sims per level, so check your town's sim count if you haven't reached the maximum yet for your current level. 2. Available houses - If one of your sims get married or moves in with another sim, his or her house will become vacant. A green house means it's vacant. You can add a new sim to that vacant house or relocate another sim or an entire household to that house. 3. Available simoleons / LPs / SPs - If you plan to add a sim and have not yet exceeded your town's allowable sim count, you can add a sim by buying a house or a vacant lot. Check how much simoleons / LPs / SPs you have as against the cost of the house you want to buy. Once you have bought a new house, you will have the ability to add a new sim to your town. With all the above conditions met, you can add a sim to your town in three ways: 1. Buy a