Two three-dimensional polymeric Tb(III) and Yb(III) frameworks, namely, {[Tb-3(Hptc)(ptc)(pdc)(H2O)(6)]center dot 2H(2)O}(n) (1) and {[Yb-2(ptc)(ox)(H2O)(5)]center dot 7H(2)O}(n) (2) (H(4)ptc = pyridine-2,3,5,6-tetracarboxylic acid, H(2)pdc = pyridine-3,5-dicarboxylic acid, ox = oxalate), have been synthesized by a hydrothermal method and characterized by infrared spectra, elemental analysis, powder X-ray diffraction, thermogravimetric analysis, and single-crystal X-ray diffraction. Framework 1 shows an interesting three-dimensional (8,8)-connected net with a Schlafli symbol of (3(3)center dot 4(18)center dot 5(5)center dot 6(2))(2)(3(6)center dot 4(14)center dot 5(7)center dot 6), while 2 exhibits an unusual (4,8)-connected sqc21 net with a Schlafli symbol of (3(2)center dot 4(2)center dot 5(2))(3(4)center dot 4(8)center dot 5(12)center dot 6(4)). Luminescence studies of 1 reveal that the luminescence intensity increases when the framework is dehydrated.