This book presents analyses of phonological weight in four grammatical systems and proposes novel theories to account for them. 'Weight' refers to how phonological systems refer to syllable types for various phenomena. For example, stress will often be attracted to CVː and CVC syllables, soin such a systemthese syllable types are 'heavy' while CV syllables are 'light'. The four systems discussed in the book range from sub-syllabic to phrasal levels, including stress, prosodic minimality, meter, and end-weight. The terms 'categories' and 'continua' in the subtitle refer to categorical and gradient conceptions of weight, respectively. So, important goals in this book are to demonstrate that weight has such a nature, and to provide cross-linguistic evidence for the various types. The evidence is drawn from descriptions, typological surveys, experimental results, and corpus studies. The theoretical framework employed is Optimality Theory (OT; Prince & Smolensky 2004). Maximum Entropy Harmonic Grammar (e.g. Hayes & Wilson 2008) is adopted when dealing with gradient weight effects. This book consists of six chapters. Below I summarize the theory and evidence of each chapter. I then discuss some theoretical and methodological issues raised in this book. Chapter 2 proposes a theory of vowel prominence to account for complex weight scales for stress. The core constraint is MAIN!VV, which is violated whenever stress falls on anything other than a long vowel or vocalic diphthong. This proposal differs from theories which define weight solely by moraic content (e.g. Hayes 1995). Two independent arguments are raised to support the prominence approach. First, secondary stress sometimes reveals VC to be bimoraic even in words in which VV attracts primary stress. Second, VG (where G is the first half of a geminate consonant) almost always patterns with VC, not VV, in ternary weight systems. For