This article seeks to understand why detailed personal information about accused criminals and convicts was recorded from the late 18th century in England, and why some of this information was converted into statistics from the 1820s, such that by 1860, extensive information about criminals’ physical characteristics and backgrounds was regularly collected and tabulated. These developments in record-keeping and statistics were mostly the result of local initiatives and imperatives, revealing a grass-roots information-gathering culture, with limited central government direction. Rather than primarily driven by efforts at control or the practical demands of judicial administration, the substantial amount of information recorded reveals a strong and widely held desire to understand the criminal, long before the self-conscious enterprise of ‘criminology’ was invented.