As part of the Continuing Professional Education Development Project at Pennsylvania State University, the learning styles of 148 practicing professionals (accountants, architects, clinical dietitians, and nurses) were investigated. The study objectives were: (1) to describe their learning characteristics using Kolb's Learning Style Inventory (LSI); (2) to determine, by comparison, the consistency of the attributes of these groups to the experiential learning theory on which the LSI is based; and (3) to assess whether knowledge about learning styles can be useful in the design of continuing professional education programs. The LSI is a self-description questionnaire designed to measure individual emphasis on four learning styles: concrete experience, reflective observation, abstract conceptualization and active experimentation. Intercorrelations among the four learning style scores were calculated for the total sample. Learning style similarities and differences were examined across professions using one-way ANOVA with follow-up comparisions with the Waller-Duncan K Ratio T Test. Combined scores across professions were analyzed by a 2 by 4 MANOVA. It was concluded that the LSI has some ability with groups of mature practitioners in selected professions. Guidelines for developing efficient learning packages for the four professions derived from Kolb's model for learning preferences were given. A 98-item bibliography is appended. (BS)