This paper presents the rationale behind the EQUID (Ergonomics Quality in Design) approach. The EQUID approach is a model that integrates two complementary processes. It tackles the requirements for addressing user issues according to the product life cycle, and it deals with the requirements to ensure the quality of addressing user issues in product design. The model was built upon the following aspects: challenges of product design and development (PDD) (i.e. uncertainty, complexity and consistency), PDD related to product life cycle, requirements related to organizational culture, requirements related to the design process, and stakeholders involvement.