This study examines a set of hypotheses relating obsolescence to career patterns, professional activities, and certain aspects of the organizational climate in an attempt to discern the dynamics of obsolescence among graduate engineers in the United States. Based on a sample, two measures of technical obsolescence were used. One involved the reported deterioration of knowledge in basic engineering areas of the respondent's training. The other measured the acquisition of "new" knowledge of emerging subdisciplines within engineering. The study demonstrated: (a) inverse relationship between obsolescence and level of education; (b) direct relationship between obsolescence and years of professional experience; (c) support for the hypotheses which predicted an inverse relationship between obsolescence and both responsibility and involvement; (d) direct relationship between obsolescence and administrative responsibility; (e) inverse association of individualized attributes (such as achievement, orientation) with knowledge obsolescence. The study indicated that technical obsolescence is not simply an individual problem, but an intricate process which influences and is influenced by alternative career lines, by certain professional attributes and activities, and by some aspects of the organizational milieu. (Author/PT)