Fruit firmness is one of the most important characteristics of apple quality. Unfortunately however, it is also a characteristic that tends to be influenced greatly by many preharvest and postharvest factors. Obtaining and maintaining apple fruit firmness from the orchard through to the consumer, therefore, tends to be one of the major issues facing apple producers. Apples with a firmness of less than 4.5 kg (9.9 lb) are usually rejected by consumers and, therefore, this is the minimum acceptable firmness level for many soft cultivars (Prange et al., 1993). This article is a brief summary, with limited references as examples, of factors that have been shown to affect apple fruit firmness.