Linguistics is a broad discipline which encompasses several major sub-fields, such as phonetics, psycholinguistics, sociolinguistics, semantics and syntax. To make progress, these sub-fields often focus on very specific areas with little interaction between them. In this talk, I show how the integrating two often independent area--sociolinguistics and psycholinguistics--is critical to understand and advance our understanding of linguistic knowledge and use in monolinguals and bilinguals. More specifically, I examining language variation, a core concept in sociolinguistics, from a psycholinguistic perspective, as little is known about the way in which language variation is cognitively represented. Sociolinguistic research on variation usually focuses on the community level, as it takes into consideration the fact that new language variants correlate with social factors, such as age, gender, region, socioeconomic class, among others. Therefore, sociolinguistic research aims to understand why language variation occurs by studying different communities or groups of people. Psycholinguistic research, on the other hand, can show whether those changes are part of individual speakers’ internal grammar or competence and can demonstrate, with the use of experimental methods, how and where language variation emerges. I will illustrate my claim with results from a series of experimental studies on the expression of direct objects in Spanish that support the integration of these sub-disciplines. Specifically, I will show that language innovations (i.e. variation) are not always observable in spontaneous oral production (via sociolinguistic methodologies). Instead, they sometimes manifest themselves only when examining participants’ competence (via psycholinguistic methodologies).