Thin superconducting (10 to 500 nm) films of Y-Ba-Cu-O with transition temperatures (Tc) near 90 K and transition widths of less than 1 K were deposited using a excimer laser; films were superconducting down to 5 nm, but with lower Tc's. Films grown on (100) strontium titanate at temperatures above 700 K were nearly epitaxial with the Y-Ba-Cu-O c-axis normal to the substrate surface. The critical currents (Jc's) were also very high. A 100 nm film on strontium titanate had a Jc of 4x10E6 A/cm 2 at 81 K. A film deposited directly on Si showed a Tc of 50 K, however a Y-Ba-Cu-O film on epitaxial buffer layers of magnesium aluminate followed by barium titanate on Si gave a 87 K transition. Superconducting Y-Ba-Cu-O on fluorides directly showed for Mg-F a Tc of 83 K and 73 K for both Sr-F and Ba-F.