AbstractFive new quaternary chalcogenides of the 1113 family, namely BaAgTbS3, BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and CsAgUTe3, were synthesized by the reactions of the elements at 1173–1273 K. For CsAgUTe3 CsCl flux was used. Their crystal structures were determined by single‐crystal X‐ray diffraction studies. The sulfide BaAgTbS3 crystallizes in the BaAgErS3 structure type in the monoclinic space group C3,2h‐C2/m, whereas the tellurides BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and CsAgUTe3 crystallize in the KCuZrS3 structure type in the orthorhombic space group D1,27,h‐Cmcm. The BaAgTbS3 structure consists of edge‐sharing [TbS69–] octahedra and [AgS59–] trigonal pyramids. The connectivity of these polyhedra creates channels that are occupied by Ba atoms. The telluride structure features 2∞[MLnTe32–] layers for BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and 2∞[AgUTe31–] layers for CsAgUTe3. These layers comprise [MTe4] tetrahedra and [LnTe6] or [UTe6] octahedra. Ba or Cs atoms separate these layers. As there are no short Q···Q (Q = S or Te) interactions these compounds achieve charge balance as Ba2+M+Ln3+(Q2–)3 (Q = S and Te) and Cs+Ag+U4+(Te2–)3.