Genetic variation in eight populations of Avena barbata (2N = 4X = 28 chromosomes) from California was studied for five allozyme loci, two pairs of homeologous morphological loci, three quantitative characters, and response to plus and minus selection within families. The populations were chosen to include monomorphic mesic" and "xeric" ecotypes as well as populations known to be polymorphic at allozyme loci. The data were analyzed to determine the levels of quantitative character genetic variation within these populations. The null hypothesis tested is that no genetic variation for quantitative characters exists within populations which are uniform at allozyme and morphological loci. The correlation between the levels of genetic variation for allozymes and quantitative characters was examined. Quantitative genetic variation was found primarily for flowering date within and between populations of identical monomorphic allozyme types. Selection response was achieved within families from populations containing no allozyme variation. In general the populations which were polymorphic for allozymes contained higher levels of quantitative character variation. However, the level of genetic variation for allozymes did not always predict the results for quantitative variation