The Marine Corps Training Information Management System (MCTIMS) warehouses performance information regarding all mission essential tasks Marine Corps units must perform in order to execute across the full range of military operations. MCTIMS currently has a requirement for a mobile application. This application enables Marine leaders to collect unit performance data digitally in the field and quickly upload those data into MCTIMS, avoiding laborious manual input of each result. The application's concept of operations is as follows: 1) download performance evaluation criteria from MCTIMS; 2) provide leaders with inputs to capture performance ratings; 3) display results immediately following an exercise to enable After Action Reviews (AARs) and; 4) upload results to MCTIMS to support tracking of trends across the force. A prototype application, MCTIMS Mobile, was developed for testing and feasibility assessment. The application was tested in two live-fire exercises where usability and utility metrics were captured. The goals of the field tests were to informally evaluate, with Subject Matter Experts (SMEs) and proposed users, the ability of the MCTIMS Mobile tool to support productive trainee assessment and efficient data collection and measurement. The field study demonstrated support for the tool, with clear directions for improvements. The results show that the tool works as expected, but certain features can be made more intuitive and easier to use. The quantitative results were interpreted very strictly and users provided substantial constructive feedback. Consideration of the feedback received from the users led to redesign and modification of the mobile tool. MCTIMS Mobile is intended to capture more data concerning Marine performance, better data (because it is captured in real time), and data that persist in MCTIMS to improve assessments of Marines and the training the Marine Corps provides.