We conducted a survey of environmental journalists in the United States to explore individual, routine, and organizational influences on perceived knowledge of environmental issues. Using the gatekeeping theory, we found that routine and organizational factors, such as orientation to particular sources and affiliation to an organization, predict perceived knowledge. Years of covering the beat, affiliation to a news organization, and orientation to particular sources, particularly scientific and business sources, predicted perceived knowledge. In terms of individual factors, we did not find any significant influence. The relevance of these findings in the context of journalists' training is discussed.