In response to a request from the owner, the National Institute for Occupational Safety and Health (NIOSH) conducted an investigation to evaluate possible causes of back pain and discomfort resulting from working conditions at a Montessori day care facility The facility comprised two adjacent buildings, one of which housed children between the ages of six weeks and 2.75 years, and the other, children between the ages of 2.75 and four years (approximately 30 children. at each site). The school employed an all-female staff consisting of 22 teachers, administrators and assistants (full and part-time). Staff members ranged in age from 23 to 53 years (mean = 36 years); mean length of employment at the school was seven years. Although there was no history of serious injury to workers at the school (only one worker's compensation claim had been filed in the school's 21 years of operation), the owner and school administrators cited recent complaints of back and knee pain among staff members as the reason for the health hazard evaluation request.