This paper describes the development of the iSELF: an Internet-tool for Self-Evaluation and Learner Feedback to stimulate self-directed learning in ubiquitous learning environments. In ubiquitous learning, learners follow their own trails of interest, scaffolded by coaches, peers and tools for thinking and learning. Ubiquitous learning solutions include on- and off-line, formal and informal learning. To benefit from its possibilities, learners need to develop competencies for self-directed learning. To do so, a self-evaluation tool can help the learner to get insight in his/her own development, to manage and monitor his/her own learning process, to collaborate in learning, to relate the learning to 'real life' needs, and to take control over educational decisions. The iSELF is developed in an iterative process in three phases, complying to the following high level requirements: (1) Enabling learning anytime, anywhere; (2) Supporting self-directed learning; (3) Evaluating learner, learning solutions and job-needs; (4) Assessing learner competencies; (5) Using card-sort method for questionnaires; (6) Facilitating questionnaires 'under construction'; and (7) Userfriendly design. The resulting online tool contained a card-sort module, looking somewhat like a 'solitaire' game, a profile module to evaluate core competencies, and a feedback module to suggest learning possibilities in a ubiquitous learning environment. The iSELF was developed to be not only a learner tool but a scientific tool as well. Using the tool, two self-evaluation questionnaires were developed and psychometrically tested: competencies for multidisciplinary cooperation in a Network Centric Organization and self-directed learning competencies. They are used in various populations: e.g. students, employees from small and medium enterprises, crisis management organizations, and the military. Usefulness and usability of the self-evaluation tool were valued positively. It contributes to an adaptive ubiquitous learning environment in which the learner can make the educational decisions according to self-directed learning principles. The iSELF will stimulate self-directed learning in a ubiquitous learning environment and will help to create learners for life.