What is worship? Keith Pecklers, S.J., answers this important theological question by focusing on the basics of Christian worship. Beginning with the definitions of such terms as "ritual" and "liturgy" he writes in a very readable style about the historical/theological foundations of worship, tracing the evolution of Christian liturgy from the earliest centuries of the Christian era up to the reforms of Vatican II. Pecklers focuses on such liturgical issues of importance in our post-Vatican II Church as: inculturation, popular religion, and the social responsibility that authentic worship requires. He also considers some key social issues of the 21st century and their impact on our worship: the break-up of the stable parish community and decline in church attendance; the clergy shortage and priestless parishes; ecumenical liturgical cooperation and interreligious dialogue; the credibility of preaching; and how worship welcomes or excludes the marginated.