Background. Cross-linguistic research on complex structures involving movement operations such as relative clauses (RC) or wh-questions showed that typically-developing (TD) and language-impaired (SLI) children had prominent difficulties with object clauses (De Vincenci et al., 1999; Friedmann & Novogrodsky, 2011; Guasti et al., 2012; Tyack & Ingram, 1977; amongst others). Interestingly, the presence of cues, such as case-marking (Arosio et al., 2012) or word order alternations (Marinis & Van der Lély, 2007), has been shown to facilitate comprehension of these complex structures. Whether language-impaired monolingual and bilingual children are also sensitive to the same cues as their TD peers remains unexplored. Aim. This study investigated the acquisition of (non-) referential subject and object wh-questions in monolingual (L1), simultaneous (2L1) and early sequential (eL2) bilingual German-French children with or without SLI acquiring languages that provide morphological (such as case-marking in German) and word order (for French) cues. The study examines whether syntactic position, referentiality and the presence of language-specific cues affect comprehension and production of wh-questions, as well as group differences between eL2-TD, bi-SLI children and age-matched L1-SLI children. Methods. 191 children with or without SLI aged 4-to-5-years (mean AGE = 5;2) participated in two comprehension and production experiments involving picture panels with animal triplets, where the target answer was either on the left or the right side of the panel. In German, there were three morphological conditions, one providing cues on both the wh-element and the determiner (‘double cues’), or only on the wh-element (‘wh-cue’) or respectively, only on the determiner (‘NP-cue’). In French, cues were related to word order alternations with a canonical SVO order for subject vs. a non-canonical OSV pattern for object wh-questions. Results suggested that across groups, there was an effect of syntactic position (p<.001), with subject reaching higher accuracy rates than object wh-questions. There was no effect for referentiality. For cues in German, both TD and SLI children performed better on wh-questions with ‘double cues’ (p<.001) compared to ‘wh-cue’ or ‘NP-cue’. For French cues, the canonicity of word orders facilitated performance across groups. In terms of differences between TD and SLI children, the comprehension of German case-marking distinguished language-impaired from typical language development in 5-year-old (2)L1 children. For French, the failure to comprehend or limited comprehension of ESK wh-questions differentiated SLI from TD children by the age of 5 years. Further, the inability to produce or limited production of German and French object wh-questions identified SLI in (2)L1 children aged 5 years. Importantly, there were no group differences between eL2-TD, bi-SLI and L1 -SLI children. Conclusions: (1) Despite delayed acquisition, children with SLI are sensitive to the same cues that are provided in the target grammars, similarly to TD controls (2) The results concerning the children’s (in-)ability to interpret German case-marking, French ESK wh-questions or produce object wh-questions (in German and French) were linked to the nature of SLI and may provide further directives considering diagnosing SLI and clinical intervention. (3) By the age of 5 years, it remains difficult to disentangle eL2-TD acquisition from L1-SLI development on the basis of the here-investigated linguistic properties. (4) Bilingualism has no cumulative effect on SLI.