After graduating from college, Blashfield was hired by Wallace Black at Children's Press in Chicago, where she started working on a 20-volume science encyclopedia. Within a few months, she was promoted to Managing Editor, and handled all the editing and production, managed a staff of 20, and wrote a number of articles for the encyclopedia. The Young People's Science Encyclopedia was first published in 1962. Blashfield commented, "The most exciting event of my professional career was the publishing of this first encyclopedia. With that job, I was ballooned into the mainstream of publishing before I had even known where I was heading. It was a thrilling, enriching experience — being with experts in their fields, top consultants from many walks of life, and enjoying the concepts of the varied artists. I think being involved with the compiling of a major reference work of any kind is a stirring experience." In 1964, Blashfield took a job in London: "The logic of that move escapes me now, except there was no position in Chicago at the time that I was interested in, and the thought of moving to New York scared the wits out of me." While in London, her first works for the company were published - a series of Gilbert and Sullivan operas illustrated and retold for children, also published in the United States by Franklin Watts. She comments: "I also wrote a book on scientific experiments, and served as American consultant on several adult 'coffee table books,' one of which was a book of photographs by Lord Snowden, Princess Margaret's ex-husband". In 1967, Wallace Black started his own company, New Horizons Publishers, and asked Blashfield to come back to Chicago as his editor-in-chief to create a 14-volume aviation and space encyclopedia: "It seemed like too good an opportunity to miss, so I left London and came back to the United States. It was quite a challenge overseeing the work on a science encyclopedia for high school students and adults. The science was much more involved than it had been on the earlier set, but there were a lot of benefits, too The Air Force flew me to a number of special events, including the rollout of the C-5 aircraft where President Johnson spoke. I saw the launch of the first Saturn V rocket from Cape Kennedy, and I spent a lot of time in Washington, D.C." was published in 1968. After that, Blashfield moved to Washington, D.C., and worked as a freelance editor and writer. In 1976, Wallace Black, now widowed, had come to Washington on business. "We got together for dinner one night and three months later we were married." The next year, the Blacks moved to Lake Geneva, Wisconsin, and then had two children, a son, Winston, and a daughter, Chandelle. A friend introduced her to Rose Estes, who wrote a number of the early Endless Quest books for TSR. "I didn't know about TSR, even though it was only a few miles away. I had heard of the Dungeons & Dragons game, of course, but I had no idea it was published in Wisconsin." As she was already an experienced industry editor, Jean Black was brought on as Education Editor for TSR's new education department, which was intended to sell classroom modules to teachers. She worked with Jim Ward to put together an education program. The education department ultimately failed because TSR decided not to hire educational sales staff; Black would later push other educational ideas, such as books that combined World War II history with wargames, but TSR did not take advantage of these educational opportunities. Black became the Managing Editor of TSR's new Book Department, and would use the success of TSR's gamebooks to aid in the release of the Dragonlance novels. Black picked Tracy Hickman and Margaret Weis to write Dragons of Autumn Twilight and the rest of the Dragonlance Chronicles series. She also wrote a number of gamebooks, including Master of Ravenloft, Ghost Tower, and Villains of Volturnus.
