Factors affecting the development of filial preferences in chicks were investigated. Four groups of chicks were hatched and maintained in darkness. When the chicks were 20-hr old, three of these groups were exposed to an overhead light ("primed") for .5 h. When 24-hr old, all groups were placed in running wheels for 2 hr. While in the wheels one group was exposed to a visually complex pattern, one group to diffuse overhead light, and the remaining two groups (one primed and one not primed) were in darkness. All chicks were then returned to a dark incubator until their preference for a red box or a stuffed jungle fowl was measured in a simultaneous choice test either 2 hr (Test I) or 24 hr (Test II) later. At Test I the chicks which had been exposed to the complex visual pattern showed a significant preference for the fowl. Chicks in the other groups showed no preference. At Test II all groups showed a significant preference for the fowl. The results of a second experiment suggested that the later emerging preference was related to the chicks experience in the running wheel. It was concluded that the preference for the fowl will develop in entirely dark-reared chicks that are allowed a period of time in a running wheel, but that this preference will appear earlier in chicks which have had experience of a complex visual pattern.