Editor's note, March 1, 2019: The Webb Independent Review Board (WIRB) established by NASA to assess progress on its James Webb Space Telescope has provided its final briefing to NASA regarding NASA’s implemen­tation of the WIRB’s recommen­dations from a May 2018 report. NASA’s Science Mission Directorate leadership believes that this review has enhanced the likelihood of mission success. The agency has responded to this briefing, and will conduct an in-depth evaluation of risks to the mission’s schedule. The expected launch date remains March 30, 2021.