Sc8Te3 and Y8Te3 have been prepared by high-temperature solid-state techniques. The structures of both were determined from single-crystal and powder X-ray diffraction methods to be monoclinic, C2/m (No. 12) with Z = 8. Accurate lattice constants from Guinier powder film techniques at 23 degrees C for Sc8Te3 are a = 28.842(7) Angstrom, b = 3.8517(6) Angstrom, c = 22.352 (5) Angstrom, beta = 122.51(2)degrees; those for Y8Te3 are a = 31.153(7) Angstrom, b = 4.0703(4) Angstrom, c = 24.375(5) Angstrom, beta = 122.80(2)degrees. The layered structure of the title compounds consists of a complex network of chains of trans-edge-sharing metal octahedra condensed into two types of corrugated sheets that are separated by tellurium. In terms of metal-metal bonding (as judged by overlap populations), the isotypic Ti8S3 and Ti8Se3 are more 3D in aggregation, while these scandium and yttrium tellurides are 2D. This difference in dimensionality is attributed to the cooperative effects of increased anion size and decreased valence electron concentration. This is described in detail for Sc8Te3. Contrasting paramagnetic properties an reported for the two, Pauli-like for Y8Te3 and temperature-dependent for Sc8Te3, in parallel with the behaviors of the parent metals.