Papers in comparative and historical linguistics are presented. "The Independent Development of Mid Tone in Suma" (Mary Bradshaw) extends earlier research on tone change in Gbaya languages to Suma, a Gbaya language previously not included. "Diachronic Morphology: An Overview" (Brian Joseph) reviews diachronic morphological theory, focusing on what is mutable and what is stable in morphology, where morphology comes from, what triggers morphological change, and whether or not a general theory of morphological change is possible. "Divergence of Syntactic Frames and Diachronic Change" (Hyeree Kim) examines syntactic frames governed by the so-called impersonal verb in Old English and Middle English. "The Emergence of Creole Copulas: Evidence from Belize Creole" (Bettina Migge) offers evidence in support of a theory of the emergence and development of two Caribbean English Creole copulas using natural synchronic data from Belize Creole. "The Diachronic Fragmentation of Modal 'by' in Ukrainian" (Halyna Sydorenko) identifies five distinct manifestations of the modal in modern Ukranian, and also points to overlap in form and function, suggesting that the manifestations represent a morphological constellation. Articles contain references. (MSE)