  Let $X$ be a non-empty ground set and $\mathcal{P}(X)$ be its power set. A
set-labeling (or a set-valuation) of a graph $G$ is an injective set-valued
function $f:V(G)\to \mathcal{P}(X)$ such that the induced function
$f^\oplus:E(G) \to \mathcal{P}(X)$ is defined by $f^\oplus(uv) = f(u)\oplus
f(v)$, where $f(u)\oplus f(v)$ is the symmetric difference of the sets $f(u)$
and $f(v)$. A graph which admits a set-labeling is known to be a set-labeled
graph. A set-labeling $f$ of a graph $G$ is said to be a set-indexer of $G$ if
the associated function $f^\oplus$ is also injective. In this paper, we define
the notion of set-valuations of signed graphs and discuss certain properties of
signed graphs which admits certain types of set-valuations.
