This article is an introduction to weatherization methods used to improve indoor climates in historic structures using passive methods. Enormous strides have been made in this field in the past twenty years that unfortunately have not been adapted by the conservation or historic preservation fields for use in historic house museums. It is now practical to retrofit historic houses safely to the point where their performance can equal, if not exceed that of new construction. Passive improvements, by definition, are put in place, and left alone. They can radically improve building performance, stabilize indoor environments and save on energy costs. Passive improvements do not involve any moving parts, machinery, or equipment requiring monitoring, maintenance or upkeep. Most measures will pay for themselves in five years or less. -- SCMRE