The 1932 partial Serenity Prayer is the data point that clinches the argument for “R.N.” (Reinhold Niebuhr) as Wygal’s source for the prayer and as its originator.
Many of the early occurrences of the prayer were in YWCA contexts; Wygal, a longtime YWCA official, is a highly plausible disseminator for those YWCA usages. Beginning in 1937, other commentators ascribed the origination to Niebuhr, including an attribution in a booklet titled “Prayers for a Busy Day,” published by the YWCA in 1938, and there were no competing claims of authorship until some years later.
Perhaps now we can be serene knowing that the long-standing dispute over who wrote this beloved prayer has at last itself attained serenity.