I attempt to persuade the reader that externalism admits of no plausible interpretation. I argue that reliability is a concept with very different contours from epistemic justification, and that attempts to explicate justification in terms of reliability must fail. I address several other forms of externalism, and also mixed forms of justification. I then argue that externalist theories of justification cannot close the gap between mere true belief and knowledge. I suggest that a fourth condition on knowledge is required, regardless (...) of whether justification is internalist or externalist. I argue that with such a fourth condition a strong internalist theory of justification is adequate to the task that remains in making true belief knowledge. Additionally, strong internalism is more satisfying to our intuitions than externalism and mixed forms of justification. (shrink)