In October, 1998, Congress enacted the Child Online Protection Act and established the Commission on Online Child Protection (COPA) to study methods to help reduce access by minors to certain sexually explicit material, defined in the statute as harmful to minors. Congress directed the Commission to evaluate the accessibility, cost, and effectiveness of protective technologies and methods, as well as their possible effects on privacy, First Amendment values, and law enforcement. This report responds to the Congressional request. The Commission studied a wide range of child-protective technologies and methods, including filtering and blocking services; labeling and rating systems; age verification efforts; the possibility of a new top level domain for harmful-to-minors material;"greenspaces" containing only child-appropriate materials; Internet monitoring and time-limiting technology; acceptable use policies and family contracts; online resources providing access to protective technologies and methods; and options for increased prosecution against illegal online material. The report includes the following sections: (1) Introduction; (2) Technologies and Methods; (3) Recommendations; (4) Affirmative Defenses; (5) Proposed Future Work; and (6) Conclusion. A companion volume, "Personal Statements of COPA Commissioners," is appended. (MES)