![](https://image.tmdb.org/t/p/w185/sepIwNPCEhkKvFOQSjXK6tekkjR.jpg)
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The gang organizes a surprise party for Howard and Marion's 20th anniversary as clips from previous episodes are shown.
First Air Date : Jan 15, 1974
Last Air date : Sep 24, 1984
Episode : 252 Episode
Season : 11 Season
Runtime: 22:30 minutes
Studio: ABC
Country: United States of America