  We present a comprehensive analysis of constraints on the sterile neutrino as
a dark matter candidate. The minimal production scenario with a standard
thermal history and negligible cosmological lepton number is in conflict with
conservative radiative decay constraints from the cosmic X-ray background in
combination with stringent small-scale structure limits from the Lyman-alpha
forest. We show that entropy release through massive particle decay after
production does not alleviate these constraints. We further show that radiative
decay constraints from local group dwarf galaxies are subject to large
uncertainties in the dark matter density profile of these systems. Within the
strongest set of constraints, resonant production of cold sterile neutrino dark
matter in non-zero lepton number cosmologies remains allowed.
