The infants left at the London Foundling Hospital in the first twenty years of its operation have generally been classed as illegitimate. This study examines some of the characteristics of the children who entered the hospital between 1741 and 1760, and points to a far larger component of legitimate infants than has previously been suspected, up to a third being born in wedlock. The backgrounds of the children varied considerably, as did the reasons for their abandonment, with a stress on personal and economic misfortune for both married and single parents. The higher level of legitimacy among the foundlings than has been thought has implications for the illegitimacy ratio of London, pointing to relatively low levels, in common with those found for the seventeenth and nineteenth centuries.