We study the effects of grain formation in nova ejecta with double purpose: (1) to schematically model the optical and infrared luminosities, (2) to identify the anomalies of isotopic composition that should be present in large abundance in these grains. The large carbon concentration makes the rapid and efficient grain formation possible, and accounts for the peculiar luminosities observed in Nova Serpentis 1970. In the anticipated range of nova conditions, rapid addition of hot protons during the outburst produces large overabundances of 13C, 18O, 22Na, 26Al, 30Si, and perhaps others. Anomalous 14C is expected subsequent to the 13C (α,n)16O reaction, and will be trapped in grains formed by subsequent atmospheric loss. Each of these anomalies may have been detected, either on the Moon due to accretion of interstellar dust or in the carbonaceous chondrites. Perhaps nova grains are responsible
