[1] While at the Denver Post, she was part of team that won the 2000 Pulitzer Prize for Breaking News Reporting for its coverage of the Columbine High School shooting.
[5] While at the Chicago Tribune, she launched the project “Hidden Hazards: Kids at Risk" for which the newspaper won the 2008 Pulitzer Prize for Investigative Reporting.
[5][6] In 2012, Callahan along with colleagues Sam Roe and Michael Hawthorne published an investigation into the use of flame retardants in consumer products.
They were named finalists for the 2013 Pulitzer Prize for Investigative Reporting "for their exposure of manufacturers that imperil public health by continuing to use toxic fire retardants in household furniture and crib mattresses, triggering reform efforts at the state and national level.
[8] Callahan and Michael J. Berens were named finalists for the 2017 Pulitzer Prize for Investigative Reporting[9] and awarded the 2016 Worth Bingham Prize for Investigative Journalism[9] for "Suffering in Secret," a series on abuse and deaths in Illinois group homes.