Interference and dependence are closely related concepts: interference being the observable phenomenon connected with dependence. Essentially, interference means that the behaviour of some parts of a dynamic system may influence the behaviour of other parts of the same system, while dependence specifies how the semantics of sub-components of a dynamic system are related. Identifying, measuring and controlling interference is essential in many aspects of modern computer science, in particular, in security, program analysis and verification, debugging, systems specification, model checking, program manipulation, program slicing, reverse engineering, data mining, distributed databases and systems biology. In all these fields, dependency and interference play a key role in designing suitable abstractions or in partitioning complex systems into simpler ones. Reasoning about dependency and interference requires theories, models and semantics, as well as algorithms and tools for their analysis. Beginning in 2004, the series of Programming Language Interference and Dependence (PLID) workshops has been devoted to promoting and spreading cutting-edge research in this field, with a particular emphasis on unpublished results with great impact on the theoretical basis. PLID2007, which was held at the The Technical University of Denmark on 21 August 2007, was particularly successful, and constituted the ideal forum for announcing a call for papers for a special journal issue on programming language interference and dependence, which would not necessarily be restricted to PLID2007 contributions. From the many expressions of interest, we selected six contributions by leading researchers in the field, some of which had been presented at the PLID2007 workshop. The selected papers focus on foundational aspects of dependency and interference, with applications in language-based security, data-base management systems and program slicing.