Estimated traveling speed and speed limit have typically been used in population-based surveillance data to estimate crash severity. The accuracy of these measures in predicting crash severity is unknown. The Partners for Child Passenger Safety (PCPS) surveillance system offers a unique opportunity to compare these measures, as well as a novel measure of crash severity, 'self-report' delta-V, to the accepted measure of delta-V estimated during detailed crash-investigations in 118 crashes. This 'self-report' delta-V was computed from the estimated traveling speeds and direction of impact obtained from telephone interviews with drivers. These 'self-reported' delta-V estimates are modestly associated with crash-investigation delta-V estimates, with the degree of association a function of the direction of impact: when the respondent was struck from the rear, the degree of association is strong; frontal, side, and single-vehicle crashes yield weaker associations. This 'self-reported' delta-V measure, however, is a substantial improvement over use of estimated traveling speed or speed limit only.