Why build bat houses? Because bats are essential. They protect our crops, reduce use of pesticides that can cause cancer and dementia, and even help protect us from mosquito-borne diseases such as West Nile. However, they are in alarming decline, often due to loss of natural roosts. ​Armed with this handy guide from Merlin Tuttle's Bat Conservation (MTBC), you can have fun helping both bats and your neighborhood. We summarize decades of discoveries by more than a dozen leading experts to provide step-by-step instructions and diagrams for their favorite designs. Some of their conclusions will surprise you. Whether you buy or build bat houses, your success will improve when using this guide. Follow our building advice or look for vendors who meet the high standards required to gain MTBC's Seal of Approval. And if you achieve exceptional success, or even unexplained failure, let us hear from you at MerlinTuttle.org. Most of all, enjoy your bats and share your experiences with friends and neighbors!