Kilgallen's oeuvre has two sides. On the one hand, she made many drawings on paper (often endpapers of books), wood and other cheap, found materials. These works are often slightly smaller in size. On the other hand her oeuvre consists of works such as street art works in public places such as parking garages, storefronts and trains. This makes her oeuvre vulnerable: either it consists of perishable materials or it is intended, due to its public nature, to eventually fade or be broken down.