We explored the use of technology-assisted, trialogue-based tasks to measure the English language proficiency of students learning English as a second or foreign language. A presumed benefit of the system for language assessment is its suitability for use in scenario-based tasks that integrate multiple language skills. This integration allows test developers to simulate real-life language use situations by administering more authentic test tasks to strengthen the link between test performance and its interpretation as an indicator of expected success in performing real-life language use tasks. We conducted a usability study with 20 English language learners (ELLs) in grades 3 to 5, representing ten different first languages. Results suggested that the trialogue-based tasks engaged students in an authentic experience and provided evidence of their English proficiency. Perception data indicated that students perceived the trialogue-based tasks positively and understood how to respond to the virtual characters. Implications are discussed for future research and the potential of using trialogue-based assessment tasks for measuring the proficiency of young ELLs.