西洋占星术（Western Astrology），即俗称的星座，是今日最普及于坊间的占星术体系，也为具代表性的古典命理学，主要是将黄道带人为划分为十二个随中气点移动（与实际星座位置不一致）的均等的区域以分别充当实际的黄道星座。现代科学认为西洋占星术是伪科学的，就像是指鹿为马一样地将这些与实际星座毫无关系的十二中气的间隔区域说成是星座，将十二个中气点说成是星座的起始点。西洋占星术使用这些人为划分的区域充当天象，依「上行、下效」原则反映、支配着人类活动，因此十二星宫代表了十二个基本人格型态或感情特质。如同在东亚地区的一些民族根据出生年份所代表的动物来定义一个人的生肖，在很多国家，一个人的出生月份就以星座来对应。西洋占星术就是试图对应人的出生时间和这些均等划分的区域来解释人的性格和命运。西洋占星术通常分为伪恒星年派和中气春分年派两支，但伪恒星年派只不过是基于中气年派的每个等分时间点再加上25.5日，与真正的恒星年或恒星时毫无关系。

Western astrology is the system of astrology most popular in Western countries. Western astrology is historically based on Ptolemy's Tetrabiblos (2nd century AD), which in turn was a continuation of Hellenistic and ultimately Babylonian traditions.

Western astrology is largely horoscopic, that is, it is a form of divination based on the construction of a horoscope for an exact moment, such as a person's birth, in which various cosmic bodies are said to have an influence. Astrology in western popular culture is often reduced to sun sign astrology, which considers only the individual's date of birth (i.e. the "position of the Sun" at that date).