Determining the past, present and future effects of alien species on native biodiversity is a globally recognized problem. The Wall Lizard, Podarcis muralis, was introduced to Vancouver Island from Europe in 1970. To assess potential competitive interactions with the native Northern Alligator Lizard (Elgaria coerulea), I investigated several aspects of P. muralis ecology. D i h i o n along manmade corridors (e.g. roads and powerlines) and human-facilitated jump dispersal are contributing to range expansion; three separate populations currently exist. Reproductive output of P. muralis was not affected by amount eaten while gravid, but feeding level and incubation temperature affected offspring phenotypes. In comparative tests of locomotor performance, P. muralis was faster than Z. coerulea, but only at moderate temperatures. I found no effect of P. muralis dour on E. coeruela behaviour, but E. coeruela avoided cover objects that housed P. muralis. These two species use similar habitats, but were found on different substrates and mesoslopes. Based on the results of these experiments there is a potential for comvetition between these two lizard species.