If you intend to be in Germany for a longer period, you may want to be accompanied by your spouse and children. For nationals of a member state of the European Union (EU) or the European Economic Area (EEA) this will not cause any problem at all. In case accompanying family members and spouses are not citizens of one of the member states of the EU or the EEA themselves, an application for these family members is still mandatory for stays exceeding three months. However, these cases are treated rather straightforwardly by German authorities.
In general, according to the German Act on Foreign Nationals it has to be guaranteed that the family has sufficient financial means to support itself, that adequate accommodation is available (at least 13 square meters per person), and that all family members are sufficiently covered by a health insurance. As a rule, spouses and children accompanying or joining you later on must apply for a visa for family reunion (Familienzusammenführung). Upon arrival in Germany, these family members will have to apply for a regular residence permit within the first three months of their stay.
If you would like your wife or husband to follow you to Germany later on keep in mind that he or she has to be at least 18 years old and that the marriage should be concluded before settling down in Germany. Marrying after you have already entered Germany may result in longer qualifying periods for the visa of your spouse. Basic communication skills in German are also required by law for the spouse. However, this does not apply to researchers in possession of a residence permit according to §§ 19 – 21 or 38a Aufenthaltsgesetz (German Act on Foreign Nationals) or if your spouse can prove that he or she is in possession of a college degree and therefore will integrate easily.