Lexical-Functional Grammar (LFG) and Head-Driven Phrase Structure Grammar (HPSG) are both lexicalist, non-transformational, constraint-based grammatical frameworks. While they differ in many respects, they share a number of fundamental principles relevant to morphological theory and analysis, which guide the overall architecture of the grammar. The two frameworks also share a common commitment to being fully explicit and implementable, with strong links to computational implementations. This chapter provides an overview of the general approaches to morphology and the morphology-syntax interface taken by researchers working within these frameworks, illustrating the relevant aspects of each framework through discussion of morphological phenomena such as multiple exponence, auxiliaries, case stacking, morphotactics and clitics.