The purpose of this investigation was to examine the test-retest reliability of the Bayley Scales of Infant Development (BSID) (Bayley, 1969) with infants in a high-risk follow-up clinic. Eighty at-risk infants participated in this investigation. These infants were given the Mental and Motor Scales of the BSID at 6 and 12 months of age. Test-retest reliability scores of. 71 on the Mental Scale and. 69 on the Motor Scale were obtained. © 1989, Sage Publications. All rights reserved.