This article is a thoughtful and well written examination of some of the complex issues that have emerged as a result of recent improvements in the treatment of extremely low birth weight (ELBW) infants, including those who weigh 500 to 600 grams or who are believed to be 23 to 24 weeks gestation. The authors argue that the 23 to 24 week gestation period is filled with ambiguity and flexibility in practice relative to active resuscitation. However, such ambiguity and flexibility is likely to prevail whatever the boundary conditions of viability happen to be. Thus moral guidelines that inform the rescue of an infant believed to be 500 to 600 grams or 23 or 24 weeks gestation are likely to be relevant whatever the boundary conditions are.