This paper proposes a Lacanian theory of shame linked to the era of Lacan's work starting with Seminar X and the invention of the object a. From a Lacanian perspective, shame is not evoked by the exposure of a deficit, but rather by the exposure and witnessing of the divided subject's constitutive lack. This paper proposes that the affect of shame is an index pointing to the divided subject's structural lack when it is exposed and witnessed by object a instantiated as the gaze of the scopic drive and the voice of the invocatory drive. Since shame can freeze speech as well as provoke flight from the analytic work, we suggest that it is helpful for the clinician to understand how the structure of shame manifests in the patient's speech and in the transference. Clinical examples are given throughout. The paper concludes with a case discussion of Lacanian analytic work with a female patient confronted with multiple existential dilemmas that evoked shame in relationship to her body, sexuality and death.