This study examined critical periods in development to determine when offspring were most susceptible to dietary sodium manipulation leading to amphetamine sensitization. Wistar dams (n=6-8/group) were fed chow containing low (0.12% NaCl, LN), normal (1% NaCl, NN), or high sodium (4% NaCl, HN) during the prenatal or early postnatal period (birth to five weeks). Offspring were fed normal chow thereafter until testing at six months. Body weight (BW), blood pressure (BP), fluid intake, salt preference, response to amphetamine, open field behavior, plasma adrenocorticotropin hormone (ACTH), plasma corticosterone (CORT), and adrenal gland weight were measured. BW was similar for all offspring. Offspring from the prenatal and postnatal HN group had increased BP, NaCl intake, salt preference, and decreased water intake relative to NN offspring. Prenatal HN offspring had greater BP than postnatal HN offspring. In response to amphetamine, both prenatal and postnatal LN and HN offspring had increased locomotor behavior compared to NN offspring. In a novel open field environment, locomotion was also increased in prenatal and postnatal LN and HN offspring compared to NN offspring. ACTH and CORT levels 30 min after restraint stress and adrenal gland weight were greater in all LN and HN offspring compared to NN offspring. These results indicate that early life experience with low and high sodium diets, during the prenatal or early postnatal period, is a stress that produces long-term changes in responsiveness to amphetamines and to subsequent stressors.