Acceleration is an educational practice to promote gifted students. It is defined as proceeding "through an educational program at rates faster, or at younger ages, than typical" (Colangelo, Assouline, & Gross, 2004, p. xi). However, rather than being aimed at speeding up or saving time, accelerative procedures are designed to "align. .. learning opportunities with salient aspects of each student's individuality" (Lubinski & Benbow, 2000, p. 137). Hence, grade-skipping is a measure to achieve an appropriate placement that complies with the students' particular state of development irrespective of their age (see also Brody & Benbow, 2004). Being gifted in an age-based heterogeneous school setting bears the risk of a mismatch between the person and the environment (Brandtstädter, 2007; Eccles et al., 1993). Teaching designed to address academic needs of average-ability students might not provide sufficient intellectual challenge or appropriate pace of instruction, and perhaps does not satisfy the need for deep-level learning of gifted students. Particularly in their first few years at school, gifted students who are academically far ahead of their classmates do not receive instruction in the zone of their proximal development (Vygotsky, 1978) but are forced to work on things they already know (Stanley, 2000). Much of the knowledge that is new for them at school is acquired quickly, and they are able to understand many things at once. This situation can contribute to several problems, from simple boredom to underachievement, school dropout, and behavioral problems