Firmness of avocado fruit, cv Hass, was assessed by hand, and by whole fruit compression and puncture tests using an Instron. The puncture test detected softening to a greater extent than the whole fruit compression test, but neither was as good as gentle hand squeezing by an experienced assessor. Variability in softening and quality of ripe fruit was examined in relation to harvest date, tree effects, response to postharvest ethylene application, and rate of ripening. Both tree and harvest date influenced rate of ripening and internal fruit quality, and there was more variation within than between trees. Fruit which ripened rapidly were of better quality than those which ripened slowly, and different pathogens were isolated from rapid versus slow ripening fruit. The application of ethylene after storage accelerated ripening on only one of the three harvest occasions, and variability between fruit in both rate of ripening and internal quality was not reduced by this treatment. The incidence of rots was not consistently influenced by ethylene.