Casey was named Yale Younger Poet in 1972, the same year his book Obscenities was published. His other books of poetry include Millrat, published in 1996, and The Million Dollar Hole published in 2001.

Obscenities is often considered the first significant book of American poetry to come out of the Vietnam War. It has sold over 100,000 copies.

One of the more memorable stanzas from Obscenities is from the poem A Bummer:

...
If you have a farm in Vietnam
And a house in hell
Sell the farm
And go home