Forever and Ever by Janet Lambert
The irrepressible, unpredictable Campbell family returns to the United States to live in Wallaceville, the college town where Dr. Campbell had been a professor. Eighteen year old Sandra and fifteen year old Josie find small town life a fascinating novelty. Beautiful Sandra is being courted by handsome and wealthy Jay while the impetuous Josie wins the lead in the school play, falls in love with the leading man and makes her first real friend in Anna Harding McCabe. The youngest Campbell, Tenny, aged ten, also find his place in this wonderful new world.