For L equal to the unilateral or bilateral shift on a weighted sequence spa
ce, we characterize, in terms of f and the weight function, those f holomor
phic on the spectrum of L for which f (L) is a chaotic operator. For B equa
l to d/dx, the generator of left translation, on weighted L-p spaces on [0,
infinity) or R, we similarly characterize those polynomials Q for which th
e differential operator Q(B) generates a chaotic semigroup.