For various reasons, we have been studying evolution in the pre-white dwarf phase at Rochester. Our attention to the relevance of this work to planetary nebulae came as a result of calculations of the evolution of a one solar-mass iron star carried out at Rochester by S. Vila. Here the neutrino processes drive the peak luminosity to log L/L
⊙=4·26, at an effective temperature log T
eff=5·53. Although these models are brighter than 100 L
⊙ for 500 000 years, they are brighter than 1000 L
⊙ for 4000 years, and exceed 10000 L
⊙ for 900 years. We are therefore near the luminosity of the planetary-nebula nuclei, but considerably hotter, for a period of the order of the planetary lifetimes. Except for the temperature discrepancy, these models are in rough agreement with the observationally determined evolutionary sequence found by O'Dell (1963) and by Harman and Seaton (1964) and Seaton (1966).