We encourage fully enacting grounded theory (GT) to help enable organizational science to make a turn toward relational process ontologies (RPOs). RPOs unify practice and philosophy and enable more positive aspirations for organizational futures. How researchers enact GT has changed over three waves, waves which we explore in depth in terms of theoretical mindset and practice. GT is presently inadequate for the complex theorization RPOs require; therefore, we need a fourth wave of GT. Using an RPO of theory-as-historical, we guide the development of a fourth wave of GT. Theory-as-historical sees first- and second-order codes as serving different historical aims, thus second-order codes do not have to build on first-order codes. We discuss the fourth wave GT’s implications for new methods, questions, forms of knowledge, and insights, which enable organizational science to create theories that perform better organizations.