Using entropy indices and associated bootstrap tests, we describe the distribution of economic sectors across Western European regions over the 1975-2000 period. We decompose geographic concentration into its within-country and between-country components. In addition, we estimate centre-periphery gradients in sectoral location patterns and the impact of EU membership on countries' internal geography. It is found that manufacturing has become gradually more concentrated, although the locational bias towards central regions has become weaker. Conversely, market services have been relocating towards centrally located regions. EU integration appears to have strengthened countries' internal concentration trends.