We are pleased to bring you the Proceedings of the Fourth Workshop on Speech and Language Processing for Assistive Technologies (SLPAT), held in Grenoble, France on the 21st and 22nd of August, 2013. We received 23 paper submissions, of which 12 were chosen for oral presentation and another 5 for poster presentation. In addition, two demo proposals were accepted. All 19 papers are included in this volume. This workshop was intended to bring researchers from all areas of speech and language technology with a common interest in making everyday life more accessible for people with physical, cognitive, sensory, emotional or developmental disabilities. This workshop builds on three previous such workshops (co-located with NAACL HLT 2010, EMNLP in 2011, and NAACL HLT 2012) and includes a special topic, "Speech Interaction Technology for Ambient Assisted Living in the Home", which is a follow-up of two events (ILADI 2012 co-located with JEP-TALN-RECITAL 2012 and a special session in EUSIPCO 2012). The workshop provides an opportunity for individuals from research communities, and the individuals with whom they are working, to share research findings, and to discuss present and future challenges and the potential for collaboration and progress.While Augmentative and Alternative Communication (AAC) is a particularly apt application area for speech and Natural Language Processing (NLP) technologies, we purposefully made the scope of the workshop broad enough to include assistive technologies (AT) as a whole, even those falling outside of AAC. While we encouraged work that validates methods with human experimental trials, we also accepted work on basic-level innovations and philosophy, inspired by AT/AAC related problems. Thus we have aimed at broad inclusivity, which is also manifest in the diversity of our Program Committee.We are very delighted to have Prof. Mark Hawley from the University of Sheffield as invited speaker. In addition we continue our tradition of a panel of AAC users, who will speak on their experiences and perspectives as users of AAC technology. Finally, this year we also have a tour of the DOMUS "smart home" of the Laboratoire d'Informatique de Grenoble. Because of the many submissions and program points, we have for the first time extended the workshop to two full days.We would like to thank all the people and institutions who contributed to the success of the SLPAT 2013 workshop: the authors, the members of the program committee, the member of the organising committee and the invited speaker Mark Hawley. Finally, we would like to thank the Universities of Grenoble for sponsoring and hosting the workshop in the Laboratoire d'Informatique de Grenoble premises.