The authors respond to comments made by David G. Altman in his article, ""Challenges in Sustaining Public Health Interventions," Health Education & Behavior, v36 n1 p24-28 Feb 2009[see EJ826344]. They state that Altman provides a cogent and thoughtful perspective on the many challenges inherent to sustaining public health interventions. His differentiation between first-order (technical) and second-order (systems-oriented) intervention approaches provides a promising framework for conceptualizing and studying sustainability. Nonetheless, Fagen and Flay believe that any effort to sustain public health programs should utilize both first- and second-order interventions, and they advocate more and better sustainability research that tests for the most effective mix of intervention types.