This paper explains when and how to integrate aspects of usability engineering in the agile development process proposed by the InterMod methodology. The aim of InterMod is to facilitate the accurate development of high-quality interactive software. This is accomplished by means of agile software engineering activities and continuous assessment in which certain usability evaluation techniques have been suitably integrated. Such integration brings benefits to the early steps of the development process. On the one hand, this integration promotes development tailored to users' expectations. On the other hand, it helps to plan the agile process of activities. In terms of developing a mobile application, the use of prototypes in early stages of the development process has been considered as being quite beneficial for organizing the workflow. Using heuristic evaluations and user tests has also been valuable when grouping evaluations in specific iterations.