We introduce the concept of an L 1 full group associated with a measure-preserving action of a Polish normed group on a standard probability space. Such groups are shown to carry a natural separable complete metric, and are thus Polish. Our construction generalizes L 1 full groups of actions of discrete groups, which have been studied recently by the first author.We show that under minor assumptions on the actions, topological derived subgroups of L 1 full groups are topologically simple and -when the acting group is locally compact and amenable -are whirly amenable and generically two-generated.For measure-preserving actions of the real line (also known as measure-preserving flows), the topological derived subgroup of an L 1 full groups is shown to coincide with the kernel of the index map, which implies that L 1 full groups of free measure-preserving flows are topologically finitely generated if and only if the flow admits finitely many ergodic components. The latter is in a striking contrast to the case of Z-actions, where the number of topological generators is controlled by the entropy of the action.