Darsapaurnamasa is a ritual that has to be performed once in a lunar month. In Sanskrit, the term darsha and purnamasa refers to the new and the full moon days, respectively. Hence the name itself suggests this ritual consists of two parts, which are to be performed on the new and the full moon days.
The first part of the ritual commences on the forenoon of the full moon day and ends on the forenoon of the successive day. Similarly, the second part of the ritual commences on the forenoon of the new moon day and ends on the forenoon of the successive day.
Darshapaurnamasya is generally considered a nityakarma, because pratyavaya (occurrence of sin) is mentioned in the event of non-performance of this, as in the case of sandhyavandanam. But by a suitable change in the sankalpa and the substances used for oblations, darsapaurnamasya may also be performed as a kamyakarma to yield the desired result. The numbers of priests required for performing this karma are four.