Background:
Summer vacations interrupt the rhythm of learning and may result in a loss of knowledge and skills.

Materials and methods:
This study investigates summer learning losses in an Austrian sample with nine-week summer vacations. The results show losses as well as gains for students in lower secondary education (182 students between 10 and 12 years old).

Results:
Students experienced losses in arith-metic problem solving (measured by the HAWIK IV intelligence test) and spelling (measured by the Salzburg Reading-Screening, SLS-8), but gains in reading (measured by the standard-ized spelling test HSP 5-9).

Conclusions:
Losses or gains in a knowledge domain appear to depend on the degree of practice during the summer vacation. Contrary to American studies, students could make up for their losses within nine weeks following the re-start of school. In addition, socio-economic variables such as the mother's educational background had a small impact on sum-mer learning losses in arithmetic problem solving.