The aim of this research was to explore factors that are related with hatchability in the field. Data from 3 Dutch hatcheries for the years 2004, 2005, and 2006 were analyzed using a random regression model with the method of restricted maximum likelihood. In total, 24,234 batches of 724,750,444 eggs, originating from 511 breeder flocks, were included. Annually, 241,583,481 eggs were set on average, which is 37% of the total annual eggs set in the Netherlands. A significant difference in hatchability among eggs from different breeder flocks was found. Hatchability was significantly related with flock age, egg storage length, strain, feed company, season, year, as well as hatchery (P < 0.001). There was also significant interaction between flock age and age at first delivery, egg storage length at hatchery, strain, feed company, and season. Other 3-way interaction terms were also significant. The variation in hatchability was larger among the breeder farms than within breeder farms. The average estimated difference in hatchability among the hatcheries was 8%. The average estimated hatchability at 25 wk of age was 66%; it increased to 86% between 31 and 36 wk and decreased to 50% at 65 wk of age. On average, an extra day of storage until d 7 reduced hatchability by 0.2% and from d 7 to 14 by 0.5%. Eggs from older flocks were less sensitive to prolonged storage, whereas they were more sensitive to season. Hatchability was greater during late summer than during spring. The average estimated differences in hatchability among strains and feed companies of the breeder farms were 8 and 2%, respectively. Based on the relations found, optimization of hatchery results depends not only on good management at the hatchery but also on the hatching egg quality and therefore on the breeder farm management. It can be concluded that production data that are collected by the hatcheries can be used to adjust the management decisions at hatcheries as well as breeder farms.