Millwall have been cleared of all charges relating to crowd violence at their Carling Cup clash with West Ham at Upton Park in August.
The Hammers, however, have been found guilty of breaching FA rules, while both clubs have had charges of failing to prevent racist behaviour by fans declared as "not proven" by a disciplinary panel.
The FA said in a statement: "An independent regulatory commission last week heard charges issued as a result of the serious crowd disturbances in and around the West Ham United versus Millwall fixture at Upton Park on 25 August 2009. It was alleged that both clubs failed to ensure that their supporters conducted themselves in an orderly fashion.
"The independent regulatory commission, chaired by an independent QC, found West Ham United to be in breach of FA rules in the following respects: failure to ensure their supporters refrained from violent, threatening, obscene and provocative behaviour; failure to ensure their supporters did not enter the field of play.
The commission will reconvene this Friday (15 January) to consider the issue of sanctions. The commission found all charges against Millwall not proven. The FA will now await the full written reasons from the independent commission before making any further comment."