This study attempts to determine the extent to which several hypothese
s are able to account for the illegitimate fertility decline in Englan
d in the second half of the nineteenth century. The results of a poole
d time-series analysis are consistent with the hypothesis that arise i
n working-class prosperity accounts for much of the decline. Additiona
l reasons for the decline, which cannot be ruled out with the data use
d in the analysis, include the diffusion of knowledge and acceptabilit
y of contraceptive methods and a decline in agricultural employment.