Donald Kirkpatrick was an American educator and training specialist, best known for developing the Kirkpatrick Model. This model is a widely used framework for evaluating the effectiveness of training programs. It consists of four levels: Reaction, Learning, Behavior, and Results, which help organizations assess the impact of their training initiatives. Kirkpatrick's work has significantly influenced the fields of human resource development and organizational learning. His model encourages trainers to consider not just the immediate feedback from participants, but also the long-term effects of training on performance and organizational success.