In astrology, a Grand Cross is said to occur when four planets are all separated from each other by Square aspects (90 degrees apart). A Grand Cross can also be viewed as two oppositions (180 degrees apart) separated from each other by a square. In a Grand Cross, there is one planet in each astrological element (fire, earth, air and water) but all the planets are in signs of the same modality or quality.

Because all the aspects in a Grand Cross are considered difficult aspects, the Grand Cross is seen as a source of extreme tension whereby various aspects of the personality (represented by the planets) are working at cross purposes that serve to nullify each other. This pulls the native in many directions, ultimately leading to indecisiveness and an inability to produce concrete achievements. It is said to take extraordinary effort to overcome the conflicts in a Grand Cross.

An example of a Grand Cross would be with Saturn at 15° Virgo, Uranus at 15° Sagittarius, Neptune at 15° Gemini and Pluto at 15° Pisces. This is a mutable Grand Cross, which is said to be especially difficult with respect to the problem of maintaining focus in communication. A cardinal Grand Cross is said to cause a particular difficulty in accomplishing goals because the individual wants to accomplish everything at the same time: he/she usually ends up accomplishing very little (if anything at all). A fixed Grand Cross is said to lead to a person who is well organized but does not know where to direct their talents. Consequently, those with a fixed grand cross tend to be stuck in the same place.