Water-drinking behavior of 67 free-ranging protein supplemented and nonsupplemented beef cattle was examined between May 23 and 16 July 1986, in southcentral New Mexico. The lactating and nonlactating cows had a mean liveweight of 383 kg and were maintained as a single herd, and separated only during supplementation with an automated sorting and single animal electronic identification system. Mean daily water consumption was 57 1 day^-1 ( 16 1 ( 100 kg liveweight)^-1) at a rate of 20 1 min^-1 under mean mid-range ambient air temperatures between 14 and 24°C. Water consumed by cows supplemented at 0.7 kg head^-1 day^-1 and 1.4 kg head^-1 day^-1 fed every 5.9 days and 3.5 days, respectively, was 14 1 (100 kg liveweight)^-1  and 15 1 (100 kg liveweight)^-1 (P=0.7238), respectively. In contrast, nonsupplemented cows consumed more (P≤0.0015) water (17 1 (100 kg liveweight)^-1) than supplemented cows. Lactating cows consumed more water (P<0.0001) than nonlactating cows ( 19 1 (100 kg liveweight)^-1 and 12 1 (100 kg liveweight)^-1, respectively). One drinking event every 24 h was sufficient to satisfy cows 94% of the time. Neither supplement level nor lactation affected (P>0.05) daily watering frequency. Water intake was negatively correlated to predrinking liveweight (r= -0.19; P<0.01) and the current day's maximum ambient air temperature if greater than or equal to 30°C (r=-0.11; P<0.02). Water intake was not correlated to temperatures ≤30°C. Water consumption was positively correlated to relative humidities between 15 and 86% (r=0.17; P<0.01). Water consumption was not correlated (P>0.05) with the mid-range or maximum ambient air temperatures of the current or previous day. Our findings indicate large feedings of protein reduced water consumption, probably as a consequence of lower forage intake. Lactation increased water requirements and liveweight was a poor predictor of water needs. Water consumption is affected by biotic and abiotic factors other than those we evaluated.