The current study evaluated the use of various behavioral measures of running away with regard to (a) the differential utility of interval- versus event-based measures, (b) the differential utility of rate versus duration measures, (c) the utility of correcting for occurrence opportunity, and (d) the influence of unit of analysis (i.e., single-subject vs. grouped data). Seven different baseline measures were calculated for 84 runaways, and a unit-size analysis was conducted by constructing groups of various sizes from the original sample. An expert panel evaluated the suitability of the baseline measures for treatment evaluation. Results demonstrate the utility of evaluating duration-based measures and correcting for occurrence opportunity. Results also indicate that single-subject baselines may often be unacceptable for treatment evaluations, regardless of the type of measure selected for use. (Contains 5 figures.)