The comparative value of five measures of behavior decrement (steadiness, body sway, body sway time score, tapping rate, and critical flicker frequency) under conditions of fatigue or anxiety was studied in the collegiate competitive boxing situation. Measurements were made of 24 boxers under 4 conditions: at rest, after heavy exercise, before fighting, and after fighting. The data were subjected to analysis of variance. Measures of steadiness (hand steadiness and body sway) best satisfied the criteria for indicators of behavior decrement. "The remaining variables . . . may be made into more useful measures . . . if trial-to-trial variation and the very wide individual differences exhibited are diminished.