  The invariant approach is a powerful method for studying CP violation for
specific Lagrangians. The method is particularly useful for dealing with
discrete family symmetries. We focus on the CP properties of unbroken
$\Delta(27)$ invariant Lagrangians with Yukawa-like terms, which proves to be a
rich framework, with distinct aspects of CP, making it an ideal group to
investigate with the invariant approach. We classify Lagrangians depending on
the number of fields transforming as irreducible triplet representations of
$\Delta(27)$. For each case, we construct CP-odd weak basis invariants and use
them to discuss the respective CP properties. We find that CP violation is
sensitive to the number and type of $\Delta(27)$ representations.
