  Within the context of the weakly coupled E8 x E8 heterotic string, we study
the hidden sector of heterotic standard model compactifications to
four-dimensions. Specifically, we present a class of hidden sector vector
bundles - composed of the direct sum of line bundles only - that, together with
an effective bulk five-brane, renders the heterotic standard model entirely N=1
supersymmetric. Two explicit hidden sectors are constructed and analyzed in
this context; one with the gauge group E7 x U(1) arising from a single line
bundle and a second with an SO(12) x U(1) x U(1) gauge group constructed from
the direct sum of two line bundles. Each hidden sector bundle is shown to
satisfy all requisite physical constraints within a finite region of the Kahler
cone. We also clarify that the first Chern class of the line bundles need not
be even in our context, as has often been imposed in the model building
literature.
