Animals can be cloned using either embryonic or adult cells. Cloning from embryonic cells involves simpler procedures and yields a higher percentage of surviving offspring, but cloning from adult cells allows the desirable traits to be more easily identified and chosen.

In the most common technique for cloning from embryonic cells, the nucleus of a body cell is extracted from a very young embryo. The nucleus is inserted into a newly fertilized egg cell whose own nucleus has been removed. The egg is then placed in a culture dish until it develops into an embryo. The embryo is inserted into the womb of a female of the same species. This surrogate mother eventually bears the offspring developed from the embryo. It is possible to produce a large group of identical offspring by using this technique with a number of cells from the same embryo and using a number of surrogate mothers.

In another technique, known as embryo splitting, a very young embryo is split into two or more parts. The parts are placed in culture dishes and allowed to develop into individual, identical embryos. These embryos are then placed into a surrogate mother's womb to continue developing. Although this technique produces genetically identical offspring, some scientists do not consider it to be true cloning.

In the first technique developed for cloning adult cells, a cell taken from an adult is inserted into an unfertilized egg cell whose nucleus has been removed. The two cells are then fused with an electrical pulse. The fusion causes the cells to develop into an embryo. Each embryo is then placed into a surrogate mother's womb to continue development.

In another technique, a nucleus is removed from an adult cell and injected into an egg cell whose nucleus has been removed. The genetic material of the injected nucleus is allowed to develop for up to six hours. The cell with its new nucleus is then given a chemical bath that causes the nucleus and the cell to fuse and develop into an embryo. The embryo is then placed into a surrogate mother's womb to continue development.