A family of three children with detailed records of eruption times and sequence is presented. Dental eruption, dental maturation, skeletal ossification age, height, and weight are compared to standards for chronologic age. Two of the children showed eruption patterns within the normal range. One child, a girl 7 years 11 months of age, displayed marked advancement of eruption of the deciduous and permanent dentitions outside the limits of normal variation. This child also displayed marked advancement in anterior vertical facial growth; she was of very short stature and on the light side in weight for her chronologic age and the skeletal age corresponding to her chronologic age. Otherwise, this child had the normal physical characteristics of a 7-year-old girl. Laboratory tests to detect hyperthyroidism proved negative. No etiologic cause for this extreme advancement in dental development was evident. Marked generalized early maturation and eruption of the dentition of this girl appears to be an idiopathic phenomenon.