Cassill's prolific career writing and publishing, along with a wide array of interests beyond
fiction, make it difficult to summarize the thematic nature and concerns of his work. His stories
and novels concern bucolic life in the midwest, the life of the artist or academic, and at
times extend into autobiography. A preoccupation with the fates of couples, in alienation and
union, is exhibited in much of his fiction, as is the warring of emotional and rational impulses
in individuals and pairs. A strong visual identification is intrinsic in his prose, likely due to
his training as a visual artist. His most famous novels were Doctor Cobb's Game and Clem Anderson
but the sheer breadth of his writing and his pervasive influence as a teacher have secured Cassill's
legacy in modern fiction.