Edwina wears a harness whenever she goes in our fenced backyard (just in case.) I had a regular harness but she was very agile at getting out of it. I found a harness on a bengal cat website. It has three clasps -- one around the neck and two on her body. It looks a bit like a life jacket. She can get out of it but it takes effort. She has learned it is the only way she can go outside (and still she must be chaparoned!) so she sits next to it when she wants to go out and sits nicely when she comes in for it to be taken off. She won't walk on the leash but this way we can make sure she can't catch a bird (by stepping on the attached leash) or can pull her out of the bushes.