In this paper we study the regularity of the Szegö projection on Lebesgue and Sobolev spaces on the boundary of the unbounded model worm domain D ′ β . We consider the Hardy spaceLet W s,p (bD ′ β ) denote the Lebesgue-Sobolev space on bD ′ β . We prove that P , initially defined on the dense subspace W s,p (bD ′ β ) ∩ L 2 (bD ′ β , dσ), extends to a bounded operator P : W s,p (bD ′ β ) → W s,p (bD ′ β ), for 1 < p < ∞ and s ≥ 0.