Many of Mexico's poorest families own a small piece of land as a result of the ejido reforms of the 20th century. But there may be little on that land that can be called a house. For these families, exposure to rain and cold is a fact of life.

In 1999,San Miguel de Allende had a particularly tough winter. There was a devastating freeze, with several deaths in the countryside from lack of shelter.

Determined to help, San Miguel resident Jeffrey Brown - who had once worked as a stonemason - started brainstorming with his builder friends. With the help of consultant Irma Rosado, they secured a small donation and formed a non-profit association called "Casita Linda." Between 2001 and 2007, Casita Linda built 13 small houses using a poured-in-place cement system with reusable plastic forms.

In the winter of 2008, architecture graduate students from the Rhode Island School of Design interviewed Casita Linda families and explored design alternatives to the poured concrete construction then in use. In just over four weeks they designed and constructed Casita Linda's first adobe house, with its adaptability to design features including vaults and arches which increase the home's interior space. Most appealing is that adobe - a non-toxic material made from the very earth upon which the communities dwell - has excellent thermal qualities, keeping homes cool in the summer and warm in the winter.

Casita Linda now builds adobe brick homes in two sizes, approximately 385 and 500 square feet, at costs of approximately $7,000 to $8,000 which includes labor and materials. With two sleeping lofts and flexible main floor space, these homes provide for families of up to 11 people. As of December 2009, the 29th Casita Linda home is under construction.