Models of well being and human functioning have traditionally been based on empirical studies done with children and young adults. As part of an ongoing research program to develop and test a model of effective functioning and positive health in older adults, 31 elderly individuals (7 males, 24 females), with a mean age of 73.58 years, completed the OARS Multidimensional Functional Assessment Questionnaire, Part A (OARS MFAQ), to assess effectiveness of functioning, and an inventory based on Flanagan's (1978) research, to assess quality of life. Several physiological and psychological measures to assess human behavioral subsystems (biophysiological, perception/cognition, and interpersonal/environmental functioning) were also administered. An analysis of the results showed that effectiveness of functioning is not a unitary trait, even in a subpopulation of elderly persons. Only mental health and activities of daily living from the OARS MFAQ, and the use of leisure time, and friends and relatives from the quality of life dimension were significantly correlated. Specifically, three factors were found to be predictive of effectively functioning elderly persons: high psychological involvement, independent functioning, and acceptance. The findings suggest that the development of a model of effectiveness of functioning in elderly persons may be possible. However, refinement of the model will depend on data from a more heterogeneous sample. A 38-item reference list and four statistical tables are included. (BL)