Context-Oriented Software Development with Generalized Layer Activation Mechanism -- Developing and Verifying Response Specifications in Hierarchical Event-Based Systems -- Programming with Emergent Gummy Modules -- Generalized Layer Activation Mechanism for Context-Oriented Programming -- Modular Reasoning in the Presence of Event Subtyping -- Software Unbundling: Challenges and Perspectives -- Dynamic Dispatch for Method Contracts through Abstract Predicates.

The LNCS Transactions on Modularity and Composition are devoted to all aspects of software modularity and composition methods, tools, and techniques, covering requirement analysis, design, implementation, maintenance, and evolution.  The focus of the journal also includes modelling techniques, new paradigms and languages, development tools, measurement, novel verification and testing approaches, theoretical foundations, and understanding interactions between modularity and composition. This, the first issue of the Transactions on Modularity and Composition, consists of two sections. The first one, guest edited by Patrick Eugster, Mario S�udholt, and Lukasz Ziarek, is entitled "Aspects, Events, and Modularity" and includes papers focusing on context-oriented software development, specifications for even-based systems, and development of modular software. The second section, guest edited by Gary T. Leavens, contains journal versions of selected papers from Modularity 2015, which was held in March 2015, in Fort Collins, Colorado, USA. Topics covered by the papers in this section include software unbundling, layer activation in context-oriented programming, modular reasoning in event-based languages, and dynamic dispatch for method contracts using abstract predicates.