Over the past few decades it has become clear that the immune system and especially T cells are instrumental in achieving a long and healthy life. The European Union (EU) previously supported several pan-European research projects coordinated from Tuebingen, Germany, aimed at providing a better understanding of immunosenescence. For 3 years, until the end of 2005, the EU is supporting a project called T cells in aging (T-CIA). The aim of T-CIA is to spy out and combine current efforts in immunology, molecular biology, and gerontology for a better understanding of why the elderly often have dysregulated immune responses and are more susceptible to infections and cancer.