Rigorous Component-Based System Design (Invited Paper) -- Program Analysis Scenarios in Rascal -- K Framework Distilled -- Design and Analysis of Cloud-Based Architectures with KLAIM and Maude -- Making Maude Definitions More Interactive -- Model Checking LTLR Formulas under Localized Fairness -- Modelling and Analyzing Adaptive Self-assembly Strategies with Maude -- Formal Modeling and Analysis of Human Body Exposure to Extreme Heat in HI-Maude -- Order-Sorted Equality Enrichments Modulo Axioms -- Timed CTL Model Checking in Real-Time Maude -- Using Narrowing to Test Maude Specifications -- A Rule-Based Framework for Building Superposition-Based Decision Procedures.

This book constitutes the thoroughly refereed post-workshop proceedings of the 9th International Workshop on Rewriting Logic and its Applications, WRLA 2012, held as a satellite event of ETAPS 2012, in Tallinn, Estonia, in March 2012. The 8 revised full papers presented together with 4 invited papers were carefully reviewed and selected from 12 initial submissions and 5 invited lectures. The papers address a great diversity of topics in the fields of rewriting logic such as: foundations and models, languages, logical and semantic framework, model-based software engineering, real-time and probabilistic extensions, verification techniques, and distributed systems.