James Herne and Eugene O'Neill has been regarded as innovators of modern American drama, who discarded the conventions of the traditional melodrama. In this paper, however, Herne's Margaret Fleming and O'Neill's Long Day's Journey into Night are examined from the melodramatic perspective, and it proposes to situate them as the offsprings of the tradition of American family melodrama. Historically, family melodrama has been a dramatic form for the middle class, who considered the family as the locus of their value judgment. But while defending the bourgeois family ideology, family melodrama also has been a "drama of excess" which subtly reveals the inner moral struggle and hysteria against its easy reconciliation. Margaret Fleming ultimately communicated to the audience its unstable happy ending and criticism toward family ideology, while it was concerned with "angel of the house" and her kind heart toward her unfaithful husband and his illegitimate son. O'Neill obviously criticized the family values as the deadlock to the individual's freedom, but he was not altogether free from the idea of family, as the Tyrones in Long Day's Journey into Night were trying to communicate with each other even after their disillusion. Hence the malleability of melodrama is conveyed by Herne and O'Neill through the transformation of the 19th century melodramatic tradition to the modern stage.