The world's mountains hold enormous societal and ecological importance. Long-term efforts to effectively monitor the complex socio-ecological systems that are embedded within such regions – many of which are rapidly changing – are urgently required to understand the driving mechanisms and processes involved, and ultimately develop sound quantitative future predictions and management strategies. Indeed, key trends can be missed if long observations are not sustained. However, the generally rugged, inhospitable, and inaccessible nature of mountainous terrain, coupled with the strong influence of topography on conditions, represent persistent challenges to obtaining informative in-situ mountain observations and sustaining these measurements across the time scales on which many underlying system dynamics operate (i.e. decades, not years). That said, the development of improved environmental sensors and options for their remote management (e.g. direct data transfer), as well as the growth of scientific networks (e.g. LTER and GEO Mountains) and their associated standards, infrastructure (eLTER RI & services like DEIMS-SDR, the GEO Mountain in-situ inventory, etc.), and knowledge sharing opportunities are improving the situation in many regards. In this context, we welcome disciplinary and interdisciplinary contributions related to mountainous regions that summarize persistent monitoring experiences, exploit long-term datasets to answer pressing research questions, and provide ideas on how common challenges associated with the development of formal research infrastructure might be best overcome.