In the present paper behaviors of mentally retarded children were recorded simultaneously on real time and time lapse video recorders. Behaviors on the time lapse recordings occurred at a rate 12 times faster than they actually occurred in real time resulting in a 92 percent reduction in the time required to score the tapes. Reliability estimates from real time and time lapse records were high and correspondence between the two methods was good. The limitations of time lapse and the feasibilities for the extended use of time lapse video recorders in behavioral and ecobehavioral assessment of mentally retarded individuals are discussed.