This is the summary paper for the subjects of plasma stability, energetic particles, waves and current drive at the 20th IAEA Fusion Energy Conference, Vilamoura, Portugal, 1–6 November 2004. Material summarized herein was drawn from 65 contributed papers and 21 overview papers. The subject-wise distribution of contributed papers is shown in the following table:SubjectPapersResistive wall modes7Disruptions6Neoclassical tearing modes6Edge localized modes and the edge pedestal 13Other stability topics9Alfvén modes9Wave physics10Current drive5Total65Significant advances have been reported on the principal instabilities in magnetically confined plasmas, even extending to the burning plasma state. Wave-plasma physics is maturing and novel methods of current drive and non-inductive current generation are being developed.