Theories beyond General Relativity typically contain at least one additional scalar degree of freedom, effectively mediating an additional force. While this force must be highly suppressed in low-density environments to pass current constraints, it generically leads to deviations from General Relativity in high-density / high-curvature environments, such as neutron stars and black holes, and thus impacts their observables. I will discuss how binary systems in theories that feature such a fifth force can be treated using an effective field theory approach and present results regarding observables such as the power loss and the gravitational wave signal.
