Abstract.Let G be a graded nilpotent Lie group and let L be a positive Rockland operator on G. Let Ex denote the spectral resolution of L on L2(G). A sufficient condition is given under which a function m on R* is a ¿''-multiplier for L, 1 < p < oo; that is ||/0°° m(\) dExf\\p « Cp\\f\\p for a constant Ç,,/e LP'G) n L2(G). Then the same is done for an operator tr(L), where i is a unitary representation of G induced from a unitary character of a normal connected subgroup H of G. Hence the case of the Hermite operator -d2/dx2 + x2 is covered and an ¿.''-multiplier theorem for classical Hermite expansions is obtained.