Dir: Barbara Kopple. US. 2000. 113 mins.

Prod co: Cabin Creek Films. Prod: Barbara Kopple. DoP: Tom Hurwitz. Co-director/editor: Tom Haneke.

Barbara Kopple has built a successful career around cinematic-release documentaries - most recently her warts-and-all portrait of Woody Allen's jazz band, Wild Man Blues. My Generation is the culmination of a six-year project centring on the three Woodstock rock festivals of 1969, 1994 and 1999. Freshly-shot material from the two revivals is cut in with archive footage of the original event - much of it taken from Michael Wadleigh's seminal film - to make points about generational change and continuity.

Kopple has a talent for getting full access to all sides - whether it be the irate residents of Saugerties, NY, where the 1994 festival took place, or the record company executives who are discussing corporate sponsorship, percentages and spin-off merchandise such as Woodstock condoms. Montage is used to control the viewer's reaction - pointing out ironies and contradictions, moments of poignancy or hypocrisy. When jump cuts are not enough, Kopple resorts to captions - arrowing, for example, the Coke can that promoter Michael Lang is drinking from at the 1994 event, which was buoyed up by a $1 million sponsorship deal with rivals Pepsi.

The director is also good at giving the documentary format some of the emotional structure of a feature film. The first part of My Generation reaches a cathartic peak with Joe Cocker's rendition of 'With A Little Help From My Friends', in which his 1969 and 1994 performances are juxtaposed. From this point on, the music kicks in more extensively; but those expecting 'Woodstock - the sequel' will be disappointed - this is a film about people talking rather than people singing.

Concert footage of Metallica, Nine Inch Nails or Cypress Hill is used not for its own sake but to highlight contrasts (with the more focused musical protests of the Vietnam generation) or similarities (with Pete Townshend's manic guitar-bashing in 1969). Just when we are about to draw a conclusion - for example, that today's youth lack a sense of purpose - another reading is suggested; certainties fall like dominoes, and this constant questioning is part of the appeal of the film.

It all works brilliantly until the anonymous 1999 event, which is as irrelevant to the history of Woodstock as it is to Kopple's film, where it appears as an uneasy appendage. The impact of generational change is diluted when the generations are only five years apart. But My Generation remains a stimulating documentary, and one that should achieve the same kind of limited-release success as the Ali-Foreman documentary When We Were Kings.