This research examines the anomalous “null effects” of the sex ratio on rates of violent crime in previous macrolevel research. We propose a model wherein the expected positive effects on criminal violence of relatively large numbers of males is suppressed by negative indirect effects via family disruption. Several hypotheses are derived from the model and tested with race-specific data on robbery and homicide offending rates for a sample of 153 American cities. The results largely support our expectations. The sex ratio exhibits negative relationships with our indicator of family disruption — percent female-headed households — which in turn is positively related to the violent crime rates. Moreover, positive effects of the sex ratio on violent crime emerge only with controls for family disruption. We conclude with some general comments on the difficulties of inferring macrolevel relationships involving social phenomena on the basis of individual-level correlations.