Do not confuse pre-approval with pre-qualification. During the pre-qualification process, a loan officer asks you a few questions and then hands you a pre-qualification letter. The pre-approval process is much more complete as the mortgage lender does almost all the same work as a full approval. Most Realtors will not show you homes until you are pre-approved because they do not want to waste your time, their time, and the seller's time. Getting pre-approved is always at little or no cost.