It is now generally accepted that there was a fall in the number of homicide prosecutions in early modern England, perhaps signifying broader shifts in violent behaviour. So far, however, apart from J.S. Cockburn’s 1991 study of long-term developments in homicide prosecutions in Kent, there has been little in-depth analysis of this transition. This article provides a detailed study of homicide prosecutions in Cheshire over the seventeenth century, focusing on the records of the county’s Court of Great Sessions, the local equivalent of the assizes. Cheshire is the only northern county where the surviving records permit this type of analysis over the seventeenth century, and hence constitutes an important point of comparison with research completed on homicide in the south during the early modern period. Cheshire homicide cases, and especially cases categorised as manslaughter, were running at a much higher level in the first half of the century, with a peak in the 1620s. Throughout the century, homicide in the county was an overwhelmingly male activity, with men of all classes being involved. It is suggested that, in the first half of the century at least, Cheshire was a weapon-carrying culture. The decline in homicide in the second half of the century is ascribed to a set of interrelated factors including the relative social stability of the period, and the greater integration of the county into the national political system, especially after 1688, and into the national economy. These and other forces worked together to create a major transition in the culture and social psychology of the early modern English population, in which the decline of homicide was an important element.