This chapter reports the results of an experimental study into the interpretation of subject pronouns in ambiguous intra-sentential contexts in Croatian. Being a null-subject language, Croatian allows subject pronouns to be either expressed (overt) or omitted (null). Six groups of Croatian monolingual children, aged 7, 8, 9, 10, 11 and 12, and a control group of Croatian monolingual adults completed a picture selection task. The sentences consisted of a main and a subordinate clause. The main clause contained the subject and the object. The subordinate clause, which followed the main clause, featured a null or an overt pronoun which matched the main clause subject and object in gender and number. Participants had to choose between two pictures, showing either the main clause subject or object performing the action described in the subordinate clause. All groups of children differed from adults in the overt pronoun condition, choosing the subject as the antecedent of the pronoun more often than adults. However, the preferred antecedent of all participant groups was the object. In the null pronoun condition, only 8- and 10-year-olds chose the subject as the antecedent of the pronoun significantly less often than adults. This suggests that adult-like antecedent preferences of Croatian subject pronouns develop earlier with null than with overt pronouns. At what age these antecedent preferences become fully adult-like in Croatian remains to be established.