Attempts to measure self concept in the elderly have been characterized by a variety of differing definitions of self concept, and differing methodological procedures. Previous investigations have used instruments which are stereotypic and not ecologically valid for elderly, test formats which make excessive demands on some elderly persons' cognitive and sensory-motor abilities, and administration procedures which penalize the less psychologically sophisticated older person, factors precluding adequate assessment of self concept in the elderly. In order to address the limitations of previous research, the present investigation developed and tested the Ecological Q-sort, a self concept instrument designed especially for use with the elderly. Items for the Ecological Q-sort were life situations which were ecologically representative and meaningful for older persons as self-defined by them. Two forms of the Ecological Q-sort were developed: the pictorial form consisting of pictorial representations of situations plus one sentence descriptions of situations; another form consisted of only one sentence written descriptions of situations.