The Urban Mathematics Collaborative (UMC) project has the goal of contributing to the improvement of mathematics education in the inner-city schools by identifying models to enhance the professional lives of teachers and encouraging the entry of high school mathematics teachers into a larger mathematics community including mathematicians from higher education and industry. This monograph constitutes reports of case studies drawn from participant observations and interviews with teachers at 11 UMC sites. Part I explores the networks and concepts that organize the cases and discusses general themes raised in them. The first section focuses on the general problem of inner-city mathematics education, followed by an examination of the methodology of the case studies. The final section focuses on themes that interrelate teacher professionalism, empowerment, and the teaching of mathematics within urban settings. Part II includes the following studies: (1) Being There--A Mathematics Collaborative and the Challenge of Teaching Mathematics in the Urban Classroom (Cameron McCarthy); (2) Teachers on the Board (Charles Bruckerhoff); (3) A Teacher-Centered Analysis (Jan Gamradt); (4) The Politics of Mathematics (Lynda Stone); (5) Constraints in Teacher Professionalism (Ellen Madono); (6) Empowering the Professional Teacher (Eric Yonke); (7) Two Teachers' Perspectives (Robert Muffoletto); (8) Something of Our Own (Jerilynn Changar); (9) Knowledge of Growth and Professional Commitment (Anna Richert); (10) Changing To Meet the Future (Dennie Smith and Lana Smith); and (11) Professionalism and Leadership (Mary Woods Scherr). (MDH)