Frontmatter -- Table of Contents -- Introduction to the volume -- Part One - Properties and behaviour of Lenition and Frotition -- Lenition, weaking and consonantal strenght: tracing concepts through the history of phonology -- What and where? -- Posotional factors in Lenition and Fortition -- Metrical influences on fortition and lenition -- Part two - Lenition patterns in particular languages and language families -- Western Romance -- Lenition in Tuscan Italian (Gorgia Toscana) -- Germanic prosody and consonantal strength -- Slavonic -- Celtic -- Finnish Consonant Gradation -- Nivkh -- Part Three - Analysis: how Lenitition dnd Fortition work -- From Positions to Transitions: A Contour-Based Account of Lenition -- Constant Clusters in Strong and Weak Positions -- The Coda Mirror, stress and positional parameters -- Markedness, faithfulness, positions, and contexts: Lenition and Fortition in Optimality Theory -- Two directions for lenition -- Backmatter