This thesis uses an experimental approach to explore optimal gender assignment theory, an approach to gender assignment housed in Optimality Theory (Prince & Smolensky 1993/2004). Optimal gender assignment theory was proposed by Curt Rice (2006) and stipulates that grammatical gender is assigned based on a set of crucially non-ranked gender features constraints and markedness constraints. Thirty-seven participants who were bilingual in English and German received 40 sentences containing English loanwords with the definite article removed and asked to provide the appropriate gender marker and a lexical equivalency. The study found that the constraints employed and developed for optimal gender assignment theory are not applicable to English loanwords in German.