Although the exact date of when geotechnical engineers began to address environmental issues is uncertain, such issues became a primary concern in the field of Geotechnical Engineering around 1980. Thus, geotechnical engineers have been dealing with environmental issues on a formal basis for at least a quarter of a century. During the interim period, the significance of environmental issues in Geotechnical Engineering has grown to the extent such that a new sub-discipline in Geotechnical Engineering, commonly referred to as Environmental Geotechnics, has been established. As a consequence of these events, an assessment of some environmental issues that are currently of interest in Geotechnical Engineering, as well as some issues that are likely to be important in the future, is appropriate at this time. Accordingly, after a brief historical perspective, seven current and/or future environmental issues in Geotechnical Engineering are described, including the (1) long-term performance of waste containment systems, (2) acceptance of alternative barriers and barrier materials, (3) need for innovative barriers and innovative barrier materials, (4) emergence of new waste forms, (5) increasing significance of biological processes, (6) role of modeling, and (7) importance of professional identity. The significance of each issue is illustrated through one or more examples. The overall outcome of the assessment is that environmental issues will continue to represent a major sub-category within Geotechnical Engineering in the foreseeable future.