What is organisation development?

After years of argument, numerous articles and an unseemly number of less than academic discussions, the question is still around: ‘What is OD?’ Well it's presumably time to open up the issue again. But after such a long debate, some ideas must have rubbed off, so maybe — on this occasion — we'll try a different approach. Let's start with you. What do you think OD is? ‘Something to do with behavioural science’ you might say. ‘Groupie — feely — touchy sensitivity courses? — Hold on! Hasn't it got something to do with Motivation, Blakes' Grid, Role Analysis, T Groups and such? — Oh, and of course Transactional Analysis too — Getting people to understand and trust each other — that's it’.