Washington Sanatarium was a long-term care facility in the 1920s, so the croquet players may not think it's wonderland. But it is a clever title.

The sanitarium became the Washington Adventist Hospital. It was founded by the Seventh Day Adventists, who were headquartered in Takoma Park until 1989.

I remember having to play croquet in eighth grade P.E.
This still frame picture captures all the action and excitement of the game perfectly.

For the Shorpy railfans, I point out these Mallets appear to be non-articulated.

So, does the chap over toward the right have a particularly bad case of croquet elbow, or has the nurse been using her mallet to enforce the rules?