Magnetic anisotropies of ferromagnetic thin films are induced by epitaxial strain from the substrate via strain-induced anisotropy inthe orbital magnetic moment and that in the spatial distribution of spin-polarized electrons. However, the preferential orbitaloccupation in ferromagnetic metallic La1−xSrxMnO3 (LSMO) thin films studied by x-ray linear dichroism (XLD) has always been foundout-of-plane for both tensile and compressive epitaxial strain and hence irrespective of the magnetic anisotropy. In order to resolvethis mystery, we directly probed the preferential orbital occupation of spin-polarized electrons in LSMO thin films under strain byangle-dependent x-ray magnetic circular dichroism (XMCD). Anisotropy of the spin-density distribution was found to be in-plane forthe tensile strain and out-of-plane for the compressive strain, consistent with the observed magnetic anisotropy. The ubiquitousout-of-plane preferential orbital occupation seen by XLD is attributed to the occupation of both spin-up and spin-down out-ofplaneorbitals in the surface magnetic dead layer.