阴阳合历（英语：lunisolar calendar）是许多文化采用的历法，它的日期指示月球的相位，年则与太阳相关。如果太阳年以回归年定义，则阴阳合历会配合其季节；如果是采用恒星年，则历法会以预测满月所在的星座来制定。通常还有一个额外的要求，就是年终的月必须是整数，在这种情况下，大多数的年有12个月，但每2-3年就会有一年有13个月。

在天文学中是指兼顾月相周期和太阳周运动所安排的历法。一年有12个朔望月，过若干年（一般为十九岁一章）安置一个闰月，使年的平均值大约与回归年相当。夏历就是阴阳历的一种，具体的历法还包括纪年（纪元）的方法。

A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year. If the solar year is defined as a tropical year, then a lunisolar calendar will give an indication of the season; if it is taken as a sidereal year, then the calendar will predict the constellation near which the full moon may occur. Usually there is an additional requirement that the year have a whole number of months. In this case ordinary years consist of twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month.