A study was conducted to construct measures of reading competencies that are frequently needed in an occupational environment and to describe the influence of the components of reading practice on these competencies based on the conceptual framework of ethnographic psychology. The reading practices of 25 electrical engineers and 30 electronic technicians were quantified in terms of the number of minutes per month spent reading journal articles, manuals, and schematics. Simulations of reading these materials for general knowledge, specific information and for evaluation purposes were constructed. Results showed that performances on these simulations were moderately correlated for the technicians and uncorrelated for the engineers. Reading practices were independent of each other for both groups. Three out of four specific competencies were predicted from the specific practices that were expected to facilitate them, and these competencies were not associated with other practices that differed in the materials and uses of reading. Six appendixes, which make up nearly half of the document, contain copies of measures used in the study along with related reading materials, most of which are illustrated with diagrams and photographs. Eleven data tables and an extensive reference list are also included. (Author/FL)