The 42nd Hardened Electronics and Radiation Technology (HEART) Conference will be held April 19-23, 2027, at the Galt House Hotel, in Louisville, KY. The HEART Conference and the JRERE HEART−published proceedings provide a unique, classified and export controlled colloquium for authors who desire the professional recognition associated with fully refereed publications. The technical program will consist of seven to ten technical sessions of invited and contributed oral and poster presentations describing the latest observations in nuclear and space radiation effects, electromagnetic pulse phenomena, and survivability of hardened electronic systems and subsystems. Demonstration space will be provided for interactive computer programs. A limited number of attendees not able to attend an off-site Classified Session will be able to attend an alternate ITAR Tutorial.