The renaissance of double tungstate (DW) and double molybdate (DMo) crystals is due to the vigorous recent progress in growth and characterization of these materials in the form of both bulk crystals with centimeter dimensions and epitaxial layers. “Double” refers to compounds having two ions with the generic composition MT(XO4)2 (where M = Li+, Na+, or K+; T = Ln3+, Y3+, or Bi3+; and X = W6+ or Mo6+). These compounds crystallize primarily in two phases belonging to the monoclinic (C2/c) and tetragonal (l4) structures. The specific properties of both types of crystals and the major technological challenges associated with the Czochralski and top-seeded solution growth of rare-earth doped crystals are presented. The performance of specific crystals is discussed in terms of their applications as tunable, thin-disk, and ultrashort (<100 fs) pulsed lasers or as nonlinear elements for laser Raman shifting.