Beta decays have been instrumental in establishing the Standard Model as the theory of the electroweak interactions. In the era of the Large Hadron Collider, beta decays still provide very sensitive probes of physics beyond the Standard Model, which are highly competitive and complementary to searches at the energy frontier.For example, recent tensions in tests of the unitarity of the first row of the Cabibbo-Kobayashi-Maskawa quark mixing matrix might point to new physics at scales of about 10 TeV, still beyond the reach of the LHC.Because of the increasing experimental accuracy, advances in hadronic and nuclear theory are crucial to fully exploit beta decays as probes of new physics. In this talk, I will discuss the advantages of organizing various contributions to beta decays using effective field theories (EFTs). After discussing the EFT setup, I will review its application to neutron decay and to the calculation of the beta spectrum in the decay of 6He.