The synthesis and reactions of various silacyclobutenes developed by our research group are reported in this review. The nickel-catalyzed reactions of phenylethynylpolysilanes and silacyclopropenes generated photochemically from the phenylethynylpolysilanes, with phenyl(silyl)acetylenes afforded the silacyclobutene derivatives. The photolysis and thermolysis of acylpolysilanes in the presence of alkynes readily produced the silacyclobutenes. These reactions provide important routes for the synthesis of various types of the silacyclobutenes. The silacyclobutenes thus obtained underwent thermal reactions to give many types of the products, whose structures highly depend on those of the starting silacyclobutenes. The results on the theoretical studies concerning the synthesis and reactions of the silacyclobutenes have also been reported.