  New singlet scalar bosons have broad phenomenological utility and feature
prominently in many extensions of the Standard Model. Such scalars are often
taken to have Higgs-like couplings to SM fermions in order to evade stringent
flavor bounds, e.g. by assuming Minimal Flavor Violation (MFV), which leads to
a rather characteristic phenomenology. Here we describe an alternative
approach, based on an effective field theory framework for a new scalar that
dominantly couples to one specific SM fermion mass eigenstate. A simple flavor
hypothesis ensures adequate suppression of new flavor changing neutral
currents. We consider radiatively generated flavor changing neutral currents
and scalar potential terms in such theories, demonstrating that they are often
suppressed by small Yukawa couplings, and also describe the role of $CP$
symmetry. We further demonstrate that such scalars can have masses that are
significantly below the electroweak scale while still being natural, provided
they are sufficiently weakly coupled to ordinary matter. In comparison to other
flavor scenarios, our framework is rather versatile since a single (or a few)
desired scalar couplings may be investigated in isolation. We illustrate this
by discussing in detail the examples of an up-specific scalar mediator to dark
matter and a muon-specific scalar that may address the $\sim 3 \sigma$ muon
anomalous magnetic moment discrepancy.
