The short read
For an excellent introduction and ‘how to guide’ for Reminiscence Theatre, read About Reminiscence Work by Pam Schweitzer (Free Download)

The long read
Reminiscence Theatre: Making Theatre from Memories by Pam Schweitzer (Jessica Kingsley Publishers, 2007) is a detailed practical how-to guide.

Reminiscence Theatre was a totally new form that drew on the stories and memories of older people to create documentary style performances.  Sometimes a professional piece would be developed through a Reminiscence process and then tour for older audiences. Sometimes a residency would lead to a one-off performance on site. In this form, older people work with a professional creative team as co-creators, and occasionally co-performers, to make work that speaks of a particular time, place or experience. Pioneered by Pam Schweitzer and Age Exchange, this became the basis for most arts work with older people for the next three decades and has had a huge influence on participatory theatre for and with older people. Age Exchange are still going strong today, with newer companies like Re-live building on the legacy.