Negative prognostic communication is often delayed in intensive care units, which limits time for families to prepare for end-of-life. This descriptive study, informed by ethnographic methods, was focused on exploring critical care physician communication of negative prognoses to families and identifying timing influences. Prognostic communication of critical care physicians to nurses and family members was observed and physicians and family members were interviewed. Physician perception of prognostic certainty, based on an accumulation of empirical data, and the perceived need for decision-making, drove the timing of prognostic communication, rather than family needs. Although prognoses were initially identified using intuitive knowledge for patients in one of the six identified prognostic categories, utilizing decision-making to drive prognostic communication resulted in delayed prognostic communication to families until end-of-life (EOL) decisions could be justified with empirical data. Providers will better meet the needs of families who desire earlier prognostic information by separating prognostic communication from decision-making and communicating the possibility of a poor prognosis based on intuitive knowledge, while acknowledging the uncertainty inherent in prognostication. This sets the stage for later prognostic discussions focused on EOL decisions, including limiting or withdrawing treatment, which can be timed when empirical data substantiate intuitive prognoses. This allows additional time for families to anticipate and prepare for end-of-life decision-making.