In the present paper, we study the chaotic representation property for certain families X of square integrable martingales on a finite time interval [0, T ]. For this purpose, we introduce the notion of compensated-covariation stability of such families. The chaotic representation property will be defined using iterated integrals with respect to a given family X of square integrable martingales having deterministic mutual predictable covariation X,Y for all X,Y ∈ X . The main result of the present paper is stated in Theorem 5.8 below: If X is a compensated-covariation stable family of square integrable martingales such that X,Y is deterministic for all X,Y ∈ X and, furthermore, the system of monomials generated by X is total in L 2 (Ω, F X T , P), then X possesses the chaotic representation property with respect to the σ -field F X T . We shall apply this result to the case o f Lévy processes. Relative to the filtration F L generated by a Lévy process L, we construct families of martingales which possess the chaotic representation property. As an illustration of the general results, we will also discuss applications to continuous Gaussian families of martingales and independent families of compensated Poisson processes. We conclude the paper by giving, for the case of Lévy processes, several examples of concrete families X of martingales including Teugels martingales. and then we defineWe call J the space of iterated integrals generated by X .(iv) By J T we denote the linear subspace of L 2 (P) of terminal variables of iterated integrals from J . The linear spaces J (α 1 ,...,α n ) n,T and J n,T of random variables in L 2 (P) are introduced analogously from the spaces of processes J (α 1 ,...,α n ) n and J n , respectively, n ≥ 0. Now we state the definition of the chaotic representation property on the space L 2 (P).Definition 3.6. We say that X = {X (α) , α ∈ Λ} possesses the chaotic representation property (CRP) on the Hilbert space L 2 (P) = L 2 (Ω, F , P) if the linear space J T (cf. Definition 3.5 (iii)) is equal to L 2 (P).We stress that, because the spaces (L 2 (P), · 2 ) and (H 2 , · H 2 ) can be identified, we can equivalently claim that X possesses the CRP if J = H 2 .Proposition 3.4 (ii) yields that J n,T (n ≥ 1) (resp., J n (n ≥ 1)) are pairwise orthogonal closed subspaces of L 2 (P) (resp., H 2 ). Furthermore, it can easily be checked that J 0,T (resp., J 0 ) is orthogonal to J n,T (resp., J n ) for all n ≥ 1. This immediately leads to the following equivalent description of the CRP.Proposition 3.7. (i) It holds J T = ∞ n=0 J n,T (resp., J = ∞ n=0 J n ). (ii) The family X possesses the CRP if and only if L 2 (P) = ∞ n=0 J n,T (resp., H 2 = ∞ n=0 J n ).