Koala populations are in decline and measures are necessary to change the current scenario. Social marketing aims to influence an audience to change behaviour for social or environmental benefit. This paper demonstrates how social marketing was applied to achieve environmental change. A pilot program, aiming to reduce dog and koala interactions, was designed and developed with dog owners and experts including koala conservation officers and dog trainers. Experts indicated that for dogs to be taught aversion, training of basic obedience skills was necessary. Therefore, a four-week dog obedience training program was implemented, emphasising a series of behaviours including sit, stay and koala aversion. A mixed method outcome evaluation was undertaken to evaluate Leave It. The evaluation included online surveys completed by dog owners’ pre and post program, and trainer observations. Results indicate that five of seven behaviours measures were changed from baseline to follow-up, namely sit, stay, come back when called every time, wildlife aversion and stay quiet on command. Successful koala aversion was also evident in field notes from trainers. Findings of this pilot program provide evidence of the effectiveness and potential of social marketing to change behaviours in an environmental context.