While at the MBL, Just learned to handle marine invertebrate eggs and embryos with skill and understanding, and soon his expertise was in great demand by both junior and senior researchers alike. In 1915, Just took a leave of absence from Howard to enroll in an advanced academic program at the University of Chicago. That same year, Just, who was gaining a national reputation as an outstanding young scientist, was the first recipient of the NAACP's Spingarn Medal, which he received on February 12, 1915. The medal recognized his scientific achievements and his “foremost service to his race." He began his graduate training with coursework at the MBL: in 1909 and 1910 he took courses in invertebrate zoology and embryology, respectively, there. His coursework continued in-residence at the University of Chicago. His duties at Howard delayed the completion of his coursework and his receipt of the Ph.D. degree. However, in June 1916, Just received his degree in zoology, with a thesis on the mechanics of fertilization. Just thereby became one of only a handful of blacks who had gained the doctoral degree from a major university. By the time he received his doctorate from Chicago, he had already published several research articles, both as a single author and a co-author with Lillie. During his tenure at Woods Hole, Just rose from student apprentice to internationally respected scientist. A careful and meticulous experimentalist, he was regarded as "a genius in the design of experiments." He had explored other areas including: experimental parthenogenesis, cell division, hydration, dehydration in cells, UV carcinogenic radiation on cells, and physiology of development.