Beanstalk, which has changed its name to Coram Beanstalk, will retain its own identity and charity registration as a subsidiary of Coram, but will move to Coram’s offices in Bloomsbury, central London.
A spokeswoman for Coram said the merger was aimed at reducing back-office costs at Beanstalk to allow the charity to have greater impact for the children it supports, while Coram builds itself as a national centre of excellence for children.
Beanstalk is one of a number of charities that have joined Coram, with the charity’s website listing five existing members of the Coram group of charities.
No job losses are expected as a result of the merger, with Coram employing 489 people and Beanstalk 43, the spokeswoman said.
Ginny Lunn, chief executive of Beanstalk, will become divisional director for education and early years at Coram, and one Coram board member will join Beanstalk’s board.
Coram had an income of £19.7m in the 2017/18 financial year. Beanstalk’s total income was £3.8m for 2016/17.
Lunn said: "By joining the Coram group, we will ensure that our commitment to helping every child to gain the reading skills and confidence to reach their true potential can be realised with greater impact and security.
"By working together we can extend our work into new areas so that we can reach even more children who need our support."
Carol Homden, chief executive of Coram, said: "Coram is dedicated to giving every child the best possible chance in life, and learning to read is an essential skill for all our children.
"By forming Coram Beanstalk, we will be able to extend our combined impact across the country, building on complementary strengths and reach to support schools in helping children to thrive."