Gerund or Participle: What Difference Does It Make?

By Douglas Winslow Cooper

“I observed him running” or  “I observed his running”…which is correct?

First, he was running, and you were not. So we don’t need, “Running, I observed him.” 

If you are emphasizing that you observed HIM, and he happened to be running, then the first is correct, and “running” is a participle [verb form used here as an adjective].

If you are emphasizing that you were more focused on the RUNNING than on him, then the second is correct, and “running” is a gerund [verb form ending in “ing” used as a noun], and you use the possessive case of the pronoun, “his.”

I often see mistakes in cases like these.