Cells with zero counts have the potential to cause problems. Cells with zero counts are classified in two ways: fixed and random. Section 8.1 considers fixed zeros which are cells in which it is impossible to observe counts. Such cells must always be zero. Tables with fixed zeros are actually incomplete tables. Section 8.2 investigates a method that uses incomplete tables to examine category effects. The random zeros of Sect. 8.3 are cells that happen to have zero counts, but where it is possible to have positive counts. Random zeros can cause problems with finding maximum likelihood estimates.