We give a characterization of Lp(σ) for uniformly rectifiable measures σ using Tolsa’s α-numbers, by showing, for 1<p<∞ and f∈Lp(σ), that ||f||Lp(σ)∼||(∫0∞(αfσ(x,r)+|f|x,rασ(x,r))2drr)||Lp(σ)12.