The working group on the interaction of intense laser and electron beams with plasmas met at the International Centre for Theoretical Physics in Trieste from 13 to 31 August 1973. Nine countries were represented by 33 participants, who came principally from the USA (15) and the USSR (6). They were, of course, primarily theorists and hence dealt with problems of parametric instability and possible subsequent strong-turbulence effects, in laser and beam fusion applications. In particular, the questions as to whether Brillouin or Raman backscatter could become important in preventing laser absorption and whether adequately effective absorption mechanisms exist for electron beams were of great interest to the group.