The article dedicated to the problem of adaptation of the communities of Moslem immigrants in Great Britain and of their interaction with the country's authorities, which is little studied in the Russian historiography. The time limits are the period from the 1960-s, when the Moslem immigration into the United Kingdom was rapidly growing to the beginning of the XXI century inclusive. The character, the peculiarities and the evolution of the British policy of multiculturalism in particular and the interrelations of the government with the communities of religious and ethnic minorities on the territory of the country on the whole are discussed in the article. Also considered and analyzed are the processes of the radicalization of Great Britain's Islamic youth, the causes, the preconditions and the consequences of these processes and the degree of the influence on them of the policy of many cultures. The actions of the British government in response to the terrorist acts of the Moslem suicidal terrorist in London on July the 7<sup>th</sup>, 2005, and the feelings in public engendered by these events are considered, too. The author also analyzes the views and estimates of Moslem and non-Moslem public, political and religious figures, researchers concerning the problem of the radicalization and the drawing into the Great Britain's social life of the Moslem minority.