Sittlichkeit is the concept of "ethical life" or "ethical order" furthered by philosopher Georg Wilhelm Friedrich Hegel in his 1807 work Phenomenology of Spirit and his 1820/21 work Elements of the Philosophy of Right (PR).
In Elements of the Philosophy of Right, Hegel introduces the sphere of abstract right (Recht), the first of the three spheres of right he establishes. It is marked by the concept of personality and the actions of the individuals. This sphere constitutes what Isaiah Berlin would call negative freedom, which is to say, freedom ascertained through the denial of outside impetus.
The second sphere constitutes Kantian morality, and is therefore called the sphere of morality (Moralität). This sphere constitutes what Isaiah Berlin would call positive freedom, which is to say, moral autonomy. However, Hegel criticizes the deployment of Kantian morality in society for being insufficient. He explains this deficiency through pathologies of loneliness, depression and agony.
The third sphere, the sphere of ethical life (Sittlichkeit), is marked by family, civil society and the State.
To properly understand the movement from the two first spheres to the last, one must understand that Sittlichkeit's normativity transcends the individual—while Moralität may be rational and reflective, it is also individualistic. The third sphere is an attempt at describing a limited conception of the person through an appeal to the greater institutional context of the community and an attempt at bridging individual subjective feelings and the concept of general rights.
The term Sittlichkeit had been used by Hegel before in his Phenomenology of Spirit to refer to "ethical behavior grounded in custom and tradition and developed through habit and imitation in accordance with the objective laws of the community."