In March 1959, Howard McClusky introduced his Power Load Margin (PLM) theory and proposed that it be used for studying the adult years and for developing and building realistic educational programs for adults. His formula, which states that the key components of adulthood are load (the demands made upon the individual by self and society) and power (a combination of interacting factors that the individual possesses to sustain the load), is grounded in the studies in biographical psychology that were conducted by Charlotte Buhler and Elsie Frenkel-Brunswick; moreover, it was confirmed by the research in the area of changes in adult values and perceptions of reality occurring at different stages in adulthood that was conducted by R. C. Peck and W. E. Henry. McClusky did not develop a research instrument to test the PLM formula; however, in 1973 Joanne Sabol Stevenson began studies that resulted in the formation of the Margin in Life scale. It can be used as an assessment tool to identify areas of strength and weakness as well as potential power in adult students, helping them modify their life space to meet their educational goals more effectively. (MN)