Variety has a significant impact on cotton (Gossypium hirsutum L.) growth characteristics such as plant height and earliness. In order to manage these characteristics, producers usually select varieties that fit into their environment, or use plant growth regulators to reduce plant height and hasten maturity. Pentia, a relatively new plant growth regulator from BASF Corporation, uses the unique active ingredient mepiquat pentaborate. This ingredient replaces the chloride component of mepiquat chloride with five boron molecules, and is claimed to increase the uptake of Pentia compared to other plant growth regulators. The application rates range from 8-24 oz/A per treatment, with no more than 48 oz/A applied during the season. In 2005 and 2006, field experiments were conducted to evaluate the impact of Pentia application rate on varieties with different growth and maturity characteristics. This study was conducted at the Virginia Tech Tidewater Agricultural Research and Experiment Station in Suffolk, Virginia and at the Clemson University Pee Dee Research and Education Center in Florence, South Carolina. The varieties tested included an earlier maturing variety Delta Pine 444 BG/RR, a mid maturing variety Fibermax 960 BR, and a late maturing variety Delta Pine 555 BG/RR. There were four different treatments applied to each variety including an untreated check; a treatment with Pentia applied at 4 oz/A at pin-head square, 6 oz/A at match-head square, and 8 oz/A at early bloom (18 oz/A total); a treatment with Pentia applied at 8 oz/A at pin-head square, 8 oz/A at match-head square, and 12 oz/A at early bloom (24 oz/A total); and a treatment with Pentia applied at 4 oz/A at the 5-leaf stage, 8 oz/A at pin-head square, 12 oz/A at match-head square, and 16 oz/A at early bloom (40 oz/A total). All applications were applied at the same time for each treatment depending on growth stage. All treatments were evaluated on control of plant growth, maturity, and boll retention based on measurements collected and plant mapping. Preliminary data collected in Virginia in 2005 showed that plant height was significantly decreased in the Pentia treatments compared to the untreated check, as well as the Fibermax variety compared to the two Delta Pine varieties. Yield was not affected by variety; however the two higher rates (24 and 40 oz/A total) of Pentia decreased yield significantly compared to the untreated check and the lower rate of Pentia (18 oz/A total). Plant height, NAWF, plant mapping, and yield data from both years and locations will be combined and analyzed for reporting.