This article reports on one part of the National Coastal Zone Management Effectiveness study. The national study addressed how well state coastal management programs (CMPs) were implementing various goals of the Coastal Zone Management Act (CZMA). Seaport development was chosen to illustrate how well the states were managing coastal-dependent economic uses, one of the concerns of the act. From a national perspective, port development has been given only limited attention by state CMPs. All states have policies promoting water-dependent uses and most oversee regulation of port development, but less than half the states have actively identified areas for port development or paid special attention to ports in the regulatory process. Twelve "port-active" CMPs differ from this overall characterization. These 12 are examined in detail because of the size of the port sector and the importance given it by the CMP. Virtually all have policies specific to commercial seaports, including "no-sprawl" policies, delineation of areas for port development, permit criteria specific to ports, or expedited permit processes. They employ a variety of strategies for guiding port development, including regional plans, master planning, local zoning, and port-specific environmental criteria. They are active in technical assistance including grants, staff assistance, and engineering and environmental support. Organizational learning is occurring in CMPs and port organizations as a result of their interaction. Some of this learning results in changed objectives within each organization that improves achievement of the multiple objectives of the CZMA. Lending examples include regional port planning, master planning and special area management plans (SAMPs), reservation of land for future port needs, wetland mitigation banking, beneficial use of dredged material, and long-term dredging planning. Additional study is needed of the role of CMPs in managing specialized cargo facilities, dredging, and the disposal of dredged material.