Increased filling pressures, or congestion, cause symptoms of heart failure and lead to hospitalizations. A higher rate of hospitalizations determines higher mortality. The most reliable way to decrease admissions is to monitor for signs of congestion, by history and exam, intracardiac pressures or biomarkers, and to modify treatment based on these data. The role of congestion is best understood by comparison of heart failure with preserved and reduced ejection fraction. The morbidity and mortality in both conditions is almost identical. Decreased cardiac output and ventricular remodeling play a major role in patients with decreased ejection fraction but not in those with preserved ejection fraction. The key factor that is present in both conditions and determines their similarity is congestion. Decongestion, or fluid removal, is the most effective treatment for heart failure regardless of ejection fraction. Being the driving force of heart failure, congestion should be the focus of clinical and hemodynamic monitoring and therapy.