The Signaling and Gene Expression in the Immune System Conference will be an open international meeting devoted to the most recent advances in this rapidly evolving field. This meeting follows a highly successful Cold Spring Harbor Symposium held in 1999 on the same topic. The meeting will be open with attendance limited only by the facilities available to a maximum of 450 participants. Oral presentations will consist of a combination of invited presentations and presentations selected from submitted abstracts. This ensures the participation of junior and senior leaders in the field and the presentation of the most exciting results emerging at the time of the meeting. The oral presentations will be complemented by poster presentations in three poster sessions, also selected from submitted abstracts. The areas to be covered include 1) stem cells and early developmental decisions, 2) regulation of lymphocyte differentiation, 3) control of antigen receptor gene assembly, 4) antigen receptor signaling, 5) cell death, 6) T cell lineage commitment, 7) cytokine signaling, and 8) cell activation. Rather than focusing on one particular type of immune cell or process, the meeting will focus on mechanistic findings that most significantly and rigorously advance our knowledge of signal transduction and gene regulation circuitry within the immune system. The subsequent meetings (2004 and 2006) will follow a similar format and will include topics that are highly relevant at the time of the meeting.