Dorothea von der Lippe Christensen, née Frost (19 December 1847 – 28 February 1908) was a Norwegian domestic science proponent and politician.
She was born in Veøy as a daughter of vicar Christian Frost (1810–1862) and Jensine Henriette Brodtkorb (1811–1851). She became an orphan at the age of 15, and moved to attend school in Kristiania.
Helgesen finished governess school at Nissen Girls School, and also attended Eckersberg School of Painting. She worked as a governess for an attorney in Grue. In September 1871 she married physician and politician Julius Christensen (1840–1923), and moved to his hometown Sandefjord. She then became a sister-in-law of military officer Sophus Christensen, and Julius and her were parents of physician Reidar Gording and grandparents of Elisabeth Gording.
As a housewife, Christensen embarked on organizational work to improve the conditions of her group, partially influenced by travels abroad. In 1890, through a fundraiser, she established Norway's first school kitchen at Sandefjord Primary School. In the same year, a proposition to establish such kitchens in Kristiania had been rejected. The textbook Christensen wrote for the course, Kogebog for folkeskolen og hjemmet, was the first school cookbook in the country. In 1894 it was reissued, now with Helga Helgesen as co-writer. Together with Henriette Schønberg Erken, Helgesen and Christensen have been credited with forming the "first wave" of domestic science pioneers in Norway.
Christensen also established a public library, weavery house, handicraft house, shoemaker courses and a conversation club. She was a writer in local and national newspapers such as Morgenbladet. In 1897 she proposed that Norwegian housewives organize, in the article "Vi husmødre slutter os sammen" in the magazine Husmoderen. The article spurred the 1898 foundation of Kristiania Hjemmenes Vel, which grew to a national organization in 1915 (from 1934: the Norwegian Housewives' Association).