Maria Montessori was a physician in Rome in the early 1900's. She developed the Montessori program by observing young children to learn how they develop, and what types of materials engage their interest. The emphasis in a Montessori school is on hands-on learning, respect for others, and care of the self and the environment.
There are two organizations that certify and train teachers. The Association Montessori Internationale (AMI) Is the international group that maintains strict adherence to Maria Montessori's methods. The U.S. branch of the organization can be found online at www.amiusa.org. the American Montessori Society (AMS) also certifies and trains teachers. They can be found online at www.amshq.org.
To learn more about Montessori, you might want to explore some of the links below.