Trinucleotide CAG expansion mutations cause a number of progressive neurodegenerative disorders including Huntington’s disease (HD), the spinocerebellar ataxias (SCAs) 1, 2, 3, 6, 7 and 17, and spinal and bulbar muscular atrophy (SBMA). These diseases are thought to primarily result from aberrant protein gain-of-function effects, although the recent discovery of antisense transcripts at several of these loci and a new appreciation for the complexity of gene expression and epigenetic changes across the genome has raised additional possibilities. The 2013 Gordon Conference on CAG Triplet Repeat Disorders and the associated Gordon Research Seminar (GRS) will bring together scientists from around the world to discuss cutting-edge research on the molecular and cellular mechanisms of these disorders and the various therapeutic strategies which are being developed to combat them. Meeting topics will include: early clinical signs and biomarkers, proteastasis, protein structure, gene and environment interactions, inflammation and peripheral immune system biology, cell metabolism, defining endophenotypes and associated disease mechanisms, interneuron interactions, synaptic plasticity, RNA gain-of-function, stem cell biology and therapeutic strategies. Strong emphasis will be placed on training and mentoring of young scientists with time devoted to career issues. All participants will be required to present posters and some poster presenters will be selected for short talks. The collegial atmosphere of this Conference, with structured discussion sessions and opportunities for informal afternoon and evening gatherings will provide an excellent opportunity for scientists from different disciplines to brainstorm with each other and to establish interdisciplinary collaborations.