  A signed graph $\Sigma$ is a pair $(G,\sigma)$, where $G=(V,E)$ is the
underlying graph in which each edge is assigned $+1$ or $-1$ by the signature
function $\sigma:E\rightarrow\{-1,+1\}$. In this paper, we extend the
extensively applied concepts of metric dimension and resolving sets for
unsigned graphs to signed graphs. We analyze the metric dimension of some well
known classes of signed graphs including a special case of signed trees. Among
other things, we establish that the metric dimension of a signed graph is
invariant under negation.
