The term "Big Data" refers to the continuing massive expansion in the data volume and diversity as well as the speed and complexity of data processing. The use of big data underpins critical activities in all sectors of our society. Achieving the full transformative potential of big data in this increasingly digital world requires both new data analysis algorithms and a new class of systems to handle the dramatic data growth, the demand to integrate structured and unstructured data analytics, and the increasing computing needs of massive-scale analytics. We are pleased to request papers for presentation at the upcoming Fourth Workshop on Architectures and Systems for Big Data (ASBD 2014) held in conjunction with ISCA-41. The workshop will provide a forum to exchange research ideas related to all critical aspects of emerging analytics systems for big data, including architectural support, benchmarks and metrics, data management software, operating systems, and emerging challenges and opportunities. We hope to attract a group of interdisciplinary researchers from academia, industry and government research labs. To encourage discussion between participants, the workshop will include significant time for interactions between the presenters and the audience. We also plan to have a keynote speaker and/or panel session.