We are currently witnessing rapid innovation in mobile user experience (UX) research. The HCI community is creating and adapting research methods, tools, and infrastructure for mobile-specific challenges and opportunities. This workshop brings together researchers from industry and academia, designers, and creators of research tools, who faced the challenges of mobile UX research and responded with innovative approaches. We will examine the co-evolution of methods and tools by considering their goals and requirements, and how these are shared across different approaches.