This research concerns the effects that harborage limitation and habitat isolation have on German cockroach control in urban housing apartments. Standard Mason jar traps were used to survey cockroach populations, trap cockroaches for marking and population census, and detect cockroaches that moved from the original capture sites. Focus apartments (ie. apartments with large cockroach populations) were located and used for the two studies. Five focus apartments were used for the harborage limitation study. All harborage and harborage access in the kitchen and bathroom areas were sealed in three treatment apartments. These areas were not sealed in the two control apartments. Eight focus apartments were used for the habitat isolation study. Three treatment apartments had all accessways (holes and cracks) between the focus and the adjacent apartments sealed. Five control apartments were not sealed. Cockroaches in the three treatment apartments were captured, marked and released at the point of capture. Harborage limitation focus apartments were sprayed with 0. 5% chlorpyrifos in water and habitat isolation focus apartments were sprayed with a 0.25% synergized pyrethrin aerosol. Percentage control for the harborage limitation study was determined and no significant differences (P<0.1%) between treatment and control apartments were found. Percentage movement for the habitat isolation study was determined and no significant differences (P<0. 1%) between treatments and controls were noted. Neither harborage limitation nor habitat isolation would be recommended as a cockroach control technique unless they are used in concert with other control techniques.