This Technical Report contains a formalised model based on the human-centred processes described in ISO 13407, Human-centred design processes for interactive systems. It should be used in the specification, assessment and improvement of the human-centred processes in system development and operation. NOTE 1 The word formalised is used in the preceding paragraph to mean that the process descriptions in this document follow the format specified in ISO/IEC TR 15504, Information technology — Software process assessment. It should not be read as a claim that the model has any mathematical basis or rigour. NOTE 2 The difference in coverage of the model and ISO 13407 is indicated in the relevant processes (HCD 1 clause 6.2 and HCD 7 Clause 6.8). The scope of the model is based on that for ISO 13407 which has as its scope 'guidance on human-centred design activities throughout the life cycle of interactive computer-based systems.' However, whilst the intended audience for ISO 13407 is given as 'those managing the design process' this Technical Report is intended as guidance for those who are involved in the design, use and assessment of lifecycle processes for system, hardware and software. Readers of this Technical Report are expected to be familiar with ISO 13407. NOTE 3 Copyright release for the process descriptions: Users of this Technical Report may freely reproduce the process and work product descriptions contained in this document as part of any Assessment Model based on these descriptions, or as part of any demonstration of compatibility with the described processes, so that the descriptions can be used for their intended purpose.