BACKGROUND AND AIMS: Low levels of physical activity in older people are associated with a number of physical and mental health problems. However, older people remain the least active of all age groups. Providing programmes to support increased physical activity can be expensive. However, one lower-cost option is to use volunteers to deliver such programmes. There is some evidence of positive effects in volunteer-based physical activity promotion schemes, but there is a lack of well-developed and evaluated programmes. The Active Connected Engaged Project (Project ACE) aims to develop and evaluate a practical, sustainable and low cost model of using volunteers to promote active ageing. However, before we go to the expense of a large trial (around #2million), it is important to make sure that the methods and procedures for assessing its impact are going to work as intended. THE ACE PROGRAMME: The ACE programme is based on the latest evidence about what works best in promoting and sustaining physical activity in older people. The programme involves two meetings to engage participants and help them to understand the benefits of increased physical activity. Participants will then choose from a variety of physical activities that are available in their local community. An ACE activator will meet the participant up to 3 further times to review progress and to help to identify and overcome any obstacles they may encounter. Two paid neighbourhood co-ordinators will help to identify and train the twenty ACE volunteers and to identify local opportunites for physical activity. METHODS: In the first stage of the project, we will develop the ACE programme, the volunteer training course and the role of the neighbourhood co-ordinator. In the second stage, 100 older adults aged 65?85 years with low levels of physical activity will be recruited through advertising campaigns and through promotion at local events. We will use interviews with groups of patients and intervention delivery staff to find out what people thought about the programme, what worked well or badly and how it might be improved. Other information will help us to plan the future trial (e.g. recruitment and attendance rates). SERVICE USER INVOLVEMENT: Two members of the public will advise on recruitment, measurement and intervention methods, interpreting the findings and explaining the findings to the public.