Book excerpt: This book collects and organizes the original studies presented at PROMS 2015 conference on theories and applications of Rasch model. It provides useful examples of the Rasch model used to address practical measurement problems across a range of different disciplines including Item Response Theory (IRT), philosophy of measurement, dimensionality, the role of fit statistics and residuals, application, educational application, language testing, health-related research, business and industrial application and Rasch-based computer software. PROMS 2015 (Pacific Rim Objective Measurement Symposium) was held from August 20-24th 2015, in Fukuoka, Japan. The goal of this conference is to bring together the researchers from academia, universities, hospitals, industry, management sector as well as practitioners to share ideas, problems and solutions relating to the multifaceted aspects of Rasch Model.