This inquiry explores sociolinguistic variables associated with the language acquisition progress between the first and the second test sessions in three follow-up studies with German preschool children. In all three samples, children acquiring German, both Germans and immigrants, were tested twice with validated language tests within a time span of divers months. Furthermore, language skills of children were evaluated by daycare center teachers. The language proficiency of normally developed test subjects did not alter much between two test sessions, whereas children acquiring German under more challenging circumstances were still in the process of active development, mainly due to the daycare center attendance, language courses, and medical therapies. Therefore, contra-intuitively at first view, the following factors were linked with the swift language development progress: bad school marks for the language ability at the start of the daycare attendance, low age at the first test session, not systematic attendance of the daycare centers, late contact to the German language, foreign language(s) spoken at home, medical matters, and some other unpropitious language acquisition conditions.