Objective: To establish the degree of variability in thresholds for discussing withdrawal of life-sustaining therapies (WLST) in periviable infants among NICU personnel. Study Design: A vignette-style survey was administered to NICU personnel at two urban NICUs assessing likelihood of discussing WLST or support for discussing WLST (on a scale from 1 – not at all likely/supportive to 10 – extremely likely/supportive) in ten clinical scenarios. Results: Response rates ranged by clinical role from 26% to 89%. Participant responses ranged from 1-10 in five out of ten vignettes for NICU attendings, and nine out of ten vignettes for bedside nurses. Lower gestational age (22-23 versus 24-25 weeks) was associated with increased likelihood to discuss WLST in some but not all scenarios. Conclusion: NICU personnel have widely variable criteria for discussing WLST, which threatens the informed consent process surrounding resuscitation decisions in a “trial of therapy” framework.