This paper deals with the use of learning styles in technology-enhanced learning by introducing a "Unified Learning Style Model" (ULSM). The article aims at providing answers to three main questions: "What is ULSM?", "Why do we need it?" and "How can we use it?" First, a critical analysis regarding learning styles is provided; the identified challenges are addressed by proposing the use of a new model, specifically designed for TEL use. This model integrates learning preferences extracted from several traditional learning style models, related to perception modality in a way for processing and organizing information, as well as motivational and social aspects. A detailed description of the ULSM components is provided together with its rationale and its advantages. The practical applicability of the model is also shown by briefly introducing an adaptive web-based educational system based on it (called WELSA). (Contains 2 figures.)