Let H and C be sets of functions from domain X to . We say that H validly generalises C from approximate interpolation if and only if for each η > 0 and , δ ∈ (0, 1) there is m 0 (η, , δ) such that for any function t ∈ C and any probability distribution P on X, if m ≥ m 0 then with P m -probability at least 1 − δ, a sample x = (x 1 , x 2 , . . . , x m ) ∈ X m satisfies ∀h ∈ H, |h(We find conditions that are necessary and sufficient for H to validly generalise C from approximate interpolation, and we obtain bounds on the sample length m 0 (η, , δ) in terms of various parameters describing the expressive power of H.