Graphical compositions of equivalences were introduced (independently) by B. Jónsson and H. Werner in order to determine whether a subset of Eq$(X)$ (the set of all equivalences on the set $X$) is the set of all congruences of some algebra defined on $X$. Namely, a complete sublattice $L$ of Eq$(X)$ is the congruence lattice of some algebra defined on $X$ if and only if $L$ is closed under all graphical compositions. We generalize this result and prove that a similar characterization is possible for weak congruences (i.e., symmetric and transitive compatible relations).