A study of growth and development in juvenile Microtus montanus was undertaken to determine if reproductive information derived from 6-methoxybenzoxazolinone (6-MBOA) could be transferred from the maternal system to offspring prior to weaning. Mature female M. montanus were implanted intraperitoneally with 20-mm Silastic capsules containing 6-MBOA (experimental) or empty capsules (control) and then paired with males. The resulting offspring were reared in the maternal nest until 18 days old and sacrificed at 26 days of age. Data were collected on body weight, total length, and reproductive organ weights. In general, body weight and length were greater in experimental animals than in controls. Paired-testes weights did not differ significantly between control and experimental males. Uteri were significantly heavier in experimental females. The experiment was repeated and some of the female offspring from each treatment group were paired for mating to determine whether there was a breeding advantage as a result of treatment. The data strongly suggest that a transfer of information between mother and offspring occurs and that a breeding advantage accrues to females from mothers who had been treated with 6-MBOA.