Unemployment, a socio-economic phenomenon unavoidable under the capitalist mode of production in which a specific part of those members of the population who can in fact work cannot find employment (become a relatively surplus population, and form the reserve army of labour) . This is a product of the action of the general law of capitalist accumulation. As capitalism develops, the offers of working hands grow with the natural growth of the population, the ruin of small producers in competitive struggle, and the increasing involvement of children and women in capitalist production. On the other hand, the accumulation of capital is accompanied by a growth of its organic composition: the proportion of variable capital which determines the scale of the demand for labour power steadily, albeit relatively, declines despite its absolute increase. The demand for additional labour power in the process of capital accumulation also declines relatively because of the intensification of the labour of those employed, and because of frequent increase in the working hours. A surplus working population not employed in capitalist production is an inevitable companion of capitalism. But capitalism’s reserve army of labour is a relative surplus able-bodied population, since it is only surplus compared to the needs of capital for extra working hands. Unemployment is a necessary condition for the existence and development of the capitalist mode of production. First of all, the presence of the unemployed who are looking for work allows capital to not only hold wages at a low level, but also, because of the threat that they will lose their job, to force workers , to accept more intensified work, longer hours, and a lowering of the wage beneath the value of the labour power. Furthermore, the reserve army of labour is essential as a reservoir of free working hands for capitalist production, which develops spontaneously and unevenly. The relatively surplus population, or reserve army of labour, wrote Lenin, "are the workers needed by capitalism for the potential expansion of enterprises, but who can never be regularly employed... The surplus population ... is an indispensable attribute to the capitalist economy, which could neither exist nor develop without it" (V. I. Lenin, Collected 378 Works, Vol. 2, pp. 180-81). The army of the unemployed involves three basic forms: floating surplus population, agrarian ( latent) surplus population, and stagnant surplus population. The level of unemployment depends on the changing phases of the industrial cycle: it particularly rises in periods of crisis and depression, but does not fully disappear even in periods of rapid economic growth. Moreover, the number of unemployed is constantly changing because of the distribution between industries and economic regions of the capitalist countries. In the epoch of imperialism, and especially in the era of the general crisis of capitalism mass unemployment has become a chronic phenomenon in the developed capitalist countries. Unemployment rose to its highest level in the 1930s in the USA, Great Britain and Germany where 15 to 25 per cent of the able-bodied population could not find work. In post-war years, despite various measures of state-monopoly regulation of the economy, unemployment continues to exist; furthermore, capitalism’s greater instability and the deepening of its general crisis is producing higher unemployment. During the acute economic crisis in 1974-75, the number of unemployed in the developed capitalist countries exceeded 15 million and despite a subsequent economic revival of certain proportions, continued to further increase. As the economic situation became worse and the third recession in the capitalist world during the last decade unfolded, the number of unemployed in 1980 reached 19 million, i. e., double that of 1970. Simultaneously partial unemployment has become widespread, revealing itself in the use of labour power in incomplete working days or weeks because of the acute under-utilisation of production capacities. In January 1978 there were more than 3 million partially unemployed in the USA. The present conditions of the development of capitalist production and the scientific and technological revolution have led to changes in the structure of capitalist production and the structure of unemployment as well. New industries involving scientific and technical progress are rapidly expanding. The non-production sphere in the developed capitalist countries is expanding at an exceptionally fast rate. Workers in industries of declining significance are being cast out of work without the hope of quickly finding other employment since they are not equipped for work in other—especially new—- industries. Since the end of the 1960s the proportion of non-manual (intellectual) workers, who have become an extremely significant sector of the contemporary labour force (about 40 per cent in the majority of developed capitalist countries and almost 50 per cent in the USA), has grown among the unemployed. Capitalism is thus demonstrating its inability to fully use contemporary productive forces and, above all, the main productive force, the working class. This is one of the most important factors revolutionising the working class, and educating it to understand the necessity of waging a determined struggle for socialism which can eliminate unemployment and the conditions that engender it. The structural changes in the army of the unemployed bring more and more non-proletarian classes into the anti-monopoly struggle of the working class.