News aggregation has become one of the most widely practiced forms of newswork, as more news is characterized by information taken from other published sources and displayed in a single abbreviated space. This form of newsgathering has deep roots in journalism history, but creates significant tension with modern journalism's primary newsgathering practice, reporting. Aggregation's reliance on secondhand information challenges journalism's valorization of firsthand evidence-gathering through the reporter's use of observation, interviews, and documents. This dissertation examines the epistemological practices and professional values of news aggregation, exploring how aggregators gather and verify evidence and present it as factual to audiences. It looks at aggregation in relationship to the dominant values and practices of modern professional journalism, particularly those of reporting. The study employs participant observation at three news aggregation operations as well as in-depth interviews with aggregators to understand the practices of news aggregation as well as the epistemological and professional values behind them. I found that aggregation proceeds by gathering textual evidence of the forms of evidence gathered through reporting work, positioning it as a form of second-order newswork built atop the epistemological practices and values of modern journalistic reporting. Aggregators' distance from the evidence on which they base their reports lends them a profound sense of uncertainty, which they attempt to mitigate by using textual means to communicate their epistemological ambivalence to their audiences and by seeking out technologically afforded means to get closer to news evidence. Aggregators' uncertainty extends to their professional identity, where they attempt to improve their marginal professional status by articulating their own ethical values but also by emphasizing their connections to traditional reporting. Narratively speaking, however, their work does not break down traditional journalistic forms, but instead broadens the narrative horizon to conceive of individual news accounts primarily as part of larger story arcs. The study illuminates the fraught relationship between aggregation and reporting, finding that while aggregation is heavily dependent on reporting, it can be developed as a valid, professionally valued form of newswork. Ultimately, both forms of work have a crucial role to play in providing vital, engaging news to the public.