Keynote 1 -- Classes, Jim, But Not as We Know Them - Type Classes in Haskell: What, Why, and Whither -- Types, Frameworks and Modelling -- Coinductive Type Systems for Object-Oriented Languages -- Checking Framework Interactions with Relationships -- COPE - Automating Coupled Evolution of Metamodels and Models -- Aliasing and Transactions -- Making Sense of Large Heaps -- Scaling CFL-Reachability-Based Points-To Analysis Using Context-Sensitive Must-Not-Alias Analysis -- NePaLTM: Design and Implementation of Nested Parallelism for Transactional Memory Systems -- Access Control and Verification -- Implicit Dynamic Frames: Combining Dynamic Frames and Separation Logic -- Fine-Grained Access Control with Object-Sensitive Roles -- Practical API Protocol Checking with Access Permissions -- Modularity -- Adding State and Visibility Control to Traits Using Lexical Nesting -- Featherweight Jigsaw: A Minimal Core Calculus for Modular Composition of Classes -- Modular Visitor Components -- Mining and Extracting -- Debugging Method Names -- MAPO: Mining and Recommending API Usage Patterns -- Supporting Framework Use via Automatically Extracted Concept-Implementation Templates -- Refactoring -- Stepping Stones over the Refactoring Rubicon -- Program Metamorphosis -- From Public to Private to Absent: Refactoring Java Programs under Constrained Accessibility -- Keynote 2 -- Java on 1000 Cores: Tales of Hardware/Software Co-design -- Concurrency, Exceptions and Initialization -- Loci: Simple Thread-Locality for Java -- Failboxes: Provably Safe Exception Handling -- Are We Ready for a Safer Construction Environment? -- Type-Based Object Immutability with Flexible Initialization -- Concurrency and Distribution -- Security Monitor Inlining for Multithreaded Java -- EventJava: An Extension of Java for Event Correlation.-Remote Batch Invocation for Compositional Object Services -- ECOOP 2008 Banquet Speech -- to: The Myths of Object-Orientation -- The Myths of Object-Orientation.

This book constitutes the refereed proceedings of the 23rd European Conference on Object-Oriented Programming, ECOOP 2009, held in Genoa, Italy, in July 2009. The 25 revised full papers, presented together with the abstracts of 2 invited talks and the ECOOP 2008 banquet speech were carefully reviewed and selected from a total of 117 submissions. The papers cover topics such as types, frameworks and modeling; aliasing and transactions; access control and verification; modularity; mining and extracting; refactoring; concurrency, exceptions and initialization; and concurrency and distribution.