Electronic Journal of Differential Equations, Vol. 2007(2007), No. 175, pp. 1-10. Title: Self-adjoint boundary-value problems on time-scales Authors: Fordyce A. Davidson (Dundee University, Scotland, UK) Bryan P. Rynne (Dundee University, Scotland, UK) Abstract: In this paper we consider a second order, Sturm-Liouville-type boundary-value operator of the form $$ L u := -[p u^{\nabla}]^{\Delta} + qu, $$ on an arbitrary, bounded time-scale $\mathbb{T}$, for suitable functions $p,q$, together with suitable boundary conditions. We show that, with a suitable choice of domain, this operator can be formulated in the Hilbert space $L^2(\mathbb{T}_\kappa)$, in such a way that the resulting operator is self-adjoint, with compact resolvent (here, "self-adjoint" means in the standard functional analytic meaning of this term). Previous discussions of operators of this, and similar, form have described them as self-adjoint, but have not demonstrated self-adjointness in the standard functional analytic sense. Submitted June 6, 2007. Published December 12, 2007. Math Subject Classifications: 34B05, 34L05, 39A05. Key Words: Time-scales; boundary-value problem; self-adjoint linear operators; Sobolev spaces.