A positive work ethic is central to individual and career success. Yet, it can be difficult to instruct and assess work ethic with adolescents, especially those in middle and early high school who typically are not employed. This research developed an operational framework, learning experiences, and assessment of work ethic as it relates to school‐based behaviors of adolescents. The framework was based on established conceptualizations of work ethic focusing on initiative, dependability, and interpersonal skills. It was used as a basis for the Work Ethic Trait Behavior Indicators Inventory, a 30‐item performance‐based assessment instrument, and a series of work ethic lessons. Development processes for the assessment tool and procedures for schoolwide data collection are described. Recommendations and discussion are based on pilot implementation of the learning experiences and pre/post assessments of students in a ninth‐grade career exploration class taught in a large metropolitan high school.