This paper considers children's acquisition of tautosyllabic and heterosyllabic clusters in Spanish. Asymmetries in cluster production strategies within and across children's grammars will be considered as they compare to cross-linguistic findings. A general trend that emerges is a preference for low sonority in onsets, which has also be reported to occur cross-linguistically. The patterns are accounted for within an optimality theoretic framework. Accordingly, the cluster production patterns are attributed to high ranking syllable markedness constraints which outrank certain faithfulness constraints in the children's grammars. Based on the analysis, a typology of cluster production patterns is predicted to occur.