This article gives a survey of the position of migrant workers in the Belgian labor market and social security system. Total employment of migrants has increased from 114,000 in 1954 to 224,900 in 1970. In contrast to overall employment in the Belgian economy, it went on climbing till 1978, up to a 245,900 level. Beyond this year, forecasts point at a slight decrease. Since WWII, the gravity point of the sectoral division of migrant workers has shifted from minig and industry, to industry and tertiary activities. The share of industry in the employment of migrants bas remained relatively stable, in contrast to the tertiary sector, that witnessed a considerable expansion. However, the latter has not contributed substantially to the quality level of the average guest worker's job. On the whole, there is a strong correspondence between the unstable position of migrants in the labor market and their demographic characteristics on one side, their participation in the social security system on the other side. Their young family structure is reflected in a high share in family allowances and a limited appeal to pension funds. Statistical analysis at the aggregate level does not point at discriminatory practices vis-à-vis migrants and their families in social security; but at thedisaggregate level and through the inspection of laws, regulations and international conventions, it appears that non-EEC nationals, with an unstable professional career, do not have the same rights as Belgians or EEC-citizens having a confortable position in the labor market and the social security system. In order to guarantee the rights of the farmer, the author suggests to establish a citizenship entitling to full social security rights after five years of regular residence in Belgium.