This longitudinal study investigates how the reading-related activities of mothers at home relate to the development of reading skills among their kindergarten children. A total of 1,529 children (5-to-6-year-olds) were tested on word reading twice, once at the beginning and once at the end of a kindergarten year. The mothers of the children (n = 1,529) answered a questionnaire on reading-related activities with their children at home (on shared reading, teaching letters, and the teaching of reading) and on their level of education, their child's birth order, and the gender of the child. The results show that of the three reading-related activities, mothers' teaching of reading is the best predictor of the development of reading skills among kindergarten children. The results also show that good reading skills at the beginning of the kindergarten year increase the maternal teaching of reading a child subsequently receives. The results further demonstrate that girls, firstborns, and children with more highly educated mothers are more likely to become good readers by the end of the kindergarten year.