Yes, with many lenders you can lock in an interest rate until you've found the perfect house and are ready to buy. Locking in your rate protects you against rate increases for a specified period of time – usually 90 to 120 days –which gives you time to find and purchase a home and reap the rewards of the locked in rate. But it also means you might be locked in at a higher rate with that lender if the market softens.