  The inclusion of finite-size effects in the gravitational waveform templates
allows not only to constrain the internal structure of compact objects, but to
test deviations from general relativity. Here, we address the problem of tidal
effects in massless scalar-tensor theories. We introduce a new class of
scalar-type tidal Love numbers due to the presence of a time-varying scalar
dipole moment. We compute the leading-order tidal contribution in the
conservative dynamics and for the first time in the wave generation for
quasi-circular orbits. Importantly, we show that in a system dominated by
dipolar emission, such tidal effects may be detectable by LISA or third
generation detectors.
