Editing Copy editor and Proofreader Philadelphia PACatherine W. Osthaus, Principal of 5C Editing, has over twenty-five years of experience as a certified public accountant, working in both public accounting firms and not-for-profit organizations. She has prepared and proofread many financial statements, employee benefit plan documents, policy and procedure manuals, newsletters, fundraising material, correspondence, resumes, and more.


  • BSBA with a major in accounting from Shippensburg University, Shippensburg, PA
  • Certificate in copy editing from University of California, San Diego Extension, San Diego, CA
  • 40 hours of continuing professional education annually


  • Editorial Freelancers Association (EFA)
  • American Copyeditor’s Society (ACES)
  • Pennsylvania Institute of Certified Public Accountants (PICPA)
  • American Institute of Certified Public Accountants (AICPA)