The New Grove Dictionary of Jazz defines “double time” as “the apparent doubling of the tempo […] achieved by halving the prevailing note value.” A more precise term for this concept is “double-time feel.” The question of how a musical performance creates double-time feel has received little scholarly attention. Grove’s explanation is incomplete because “halving the prevailing note value” is sometimes perceived by listeners as diminution within an unchanged tempo. My hypothesis is that swing rhythm, pervasive in many styles of jazz, not only facilitates the use of double-time feel but allows for subtle gradations in its use. I offer a model that classifies rhythms according to how strongly they support (or undermine) a double-time feel in a swing rhythm context, and I apply the model to performances by Louis Armstrong and Lee Morgan. My analysis demonstrates these artists’ fine-grained control over double-time feel and suggests directions for future research.