Acres of Diamonds originated as a speech which Conwell delivered over 6,000 times around the world; it was eventually published as delivered in Conwell's home town, Philadelphia.

The central idea of the work is that one need not look elsewhere for opportunity, achievement, or fortune -- the resources to achieve all good things are present in your own community. This theme is developed by an introductory anecdote, told to Conwell by an Arab guide, about a man who wanted to find diamonds so badly that he sold his property and went off in futile search for them; the new owner of his home discovered that a rich diamond mine was located right there on the property. Conwell elaborates on the theme through examples of success, genius, service, or other virtues involving ordinary Americans contemporary to his audience: "dig in your own back-yard!".

Conwell's capacity to establish Temple University and his other civic projects largely derived from the income that he earned from this speech.