This first part describes the research and development of the NCS, from the introduction of Ewald Hering＇s theory of ＇＇the natural order system of colors＇＇ in Sweden, to a system for color notations, and finally to a compilation in a color atlas of color samples illustrating these notation and order principles. Experimental-psychological method problems regarding the assessment of the psychophysical relationship between color percepts and physical measurement data are discussed. Also described are how the color judgement experiments were performed the results of these assessments, and how NCS became established as a Swedish Standard for descriptive color notations.