CdS nanocrystals with cubic, triangular, and hexagonal geometries have been synthesized using simple wet-chemistry techniques. Analysis of the crystal structures revealed that the cubic nanocrystals have a zinc-blende crystal structure whilst the triangular and hexagonal US nanocrystals have a wurtzite crystal structure. When dried, these US nanocrystals self-assemble to form complex structures such as linear rods (see Figure), nanoarrows and dimers.