Medical errors have attracted significant interdisciplinary attention over the past two decades. Until recently, studies have primarily focused on conceptualizations, causes, and the prevention of medical mistakes. A few years ago, this focus shifted toward an examination of competent responses to critical events. In Switzerland, these efforts are reflected in the implementation of anonymous critical incident reporting systems (CIRS), which encourage institutions to learn from the human factors that contribute to medical mistakes (Scheidegger, 2005). Recent investigations in the United States have evidenced a disclosure gap, implying that phy-sicians often fail to meet patients’ disclosure expectations. Although studies have empirically identified a set of messages physicians should communicate during error disclosures, they are likely flawed because the investigations that generated them had severe methodological limita-tions. For example, most of the study designs relied on patient samples, used correlational data, and failed to utilize predictive frameworks. Furthermore, most existing studies to this date have predominantly examined informational disclosure contents, neglecting important relational messages that can influence patients’ interpretations of the error disclosure content. The proposed project is designed to fill these voids. It integrates communication competence theory (Spitzberg & Cupach, 2002), a relational message perspective (Burgoon & Hale, 1987), and typologies of symptomology and coping tactics (Spitzberg, 2002) into a conceptualization of Medical Error Disclosure Competence (MEDC). Based on these theoretical frameworks, it pro-poses a program of studies that systematically conceptualizes and operationalizes MEDC as a construct that entails three components: (1) Medical error disclosure skills (MEDS), (2) patient-perceived medical error disclosure appropriateness (PMEDA), and (3) medical error disclosure effectiveness (MEDE), which is measured by the effects of MEDS and PMEDA on theorized dis-closure outcomes. Thus, the proposed studies reflect a systematic, theoretically organized em-pirical inquiry that fills an important gap in the current international literature on critical events. This project proposal involves three empirical data collections in two stages. The first stage de-velops and empirically validates a theoretically grounded, comprehensive operationalization of medical error disclosure skills (MEDS) and their patient-perceived appropriateness (PMEDA). Two studies will be conducted to achieve this goal. The first study derives qualitative empirical data from eight focus groups with patients to identify the communicative elements that consti-tute MEDS. The second study aims to validate the focus groups’ conceptualizations of the MEDS criteria in a controlled experiment, measuring the PMEDA in respect to eight manipulated video vignettes. The second stage of the proposed research program aims to measure the effectiveness (MEDE) of PMEDA in a retrospective survey design. Assuming a successful validation of the disclosure skills construct and confirmed causal associations among the three hypothesized components of MEDC, this project lays the theoretical groundwork for an empirically based error disclosure intervention with the potential to improve patients’ and physicians’ health and quality of life.