Using a simple but general two-‐‑stage framework, this paper identifies the circumstances under
which increasing competition leads to more cost-‐‑reducing investments. The framework can, for
instance, capture increasing substitutability for different types of oligopoly models or changes from Cournot to Bertrand competition. The paper identifies four transmission mechanisms by which competition affects investment. For a firm with lower initial marginal costs (higher efficiency), a positive effect of competition on investment is more likely. Positive spillovers support
a negative effect of competition on investment. The relation between competition and investment is
not affected in an unambiguous way by the level of pre-‐‑existing competition.