Thai society is divided into upper and lower classes. At formal occasions, dress is expected to match one's social station. Appearance is very important. Wealth is greatly admired. High-status Thais often overdress, especially considering the hot climate.
Western clothing is very common. Modest clothing is recommended. General dress is informal but always neat and clean. Clothing should be stylish and cool.
For Businessmen: Pants and shirts (white or colored) with or without a tie. A light suit or jacket adds status. In the evening, dark business suits or formal traditional Thai shirts are worn. Senior executives wear light weight suits to work.
For Businesswomen: Conservative dresses or skirts and blouses (not sleeveless). Simple blouses and calf-length loose pants and long wrap-around or tube skirts are common.