Early intervention (EI) speech-language pathologists (SLPs) are required to provide culturally and linguistically responsive assessments for dual language learners (DLLs) within an increasingly diverse population. Previous research has documented gaps between SLPs' beliefs related to assessments for DLLs and their implementation of best practices within school-based and pediatric outpatient settings. The purpose of this present research study was to better understand the current knowledge, beliefs, and practices of EI SLPs in relation to the use of culturally and linguistically responsive assessment practices within the context of EI programs. A total of 134 EI SLPs completed a nationwide survey in which they were asked to describe their assessment procedures for a DLL case scenario, to identify the degree to which they agreed with a variety of assessment practices for assessing DLLs, to demonstrate their knowledge related to cultural and linguistic influences on DLLs' language development, to document their backgrounds, experiences, and current practice settings, and to provide information related to the barriers and facilitators of culturally and linguistically responsive assessment practices within their early intervention program. The data obtained from this survey were analyzed to answer research questions in three different research studies. Study 1 was designed to document EI SLPs' beliefs and practices related to assessing DLLs within EI programs. Results from Study 1 revealed that EI SLPs' beliefs related to assessing DLLs aligned with best practices. However, a substantial gap in implementation of best practices was found. Although the majority of EI SLPs attempted to account for both of a DLL's languages in their assessment practices, EI SLPs reported infrequent or very infrequent use of five out of seven best practices for assessing DLLs. Study 2 was designed to explore the relationships between EI SLPs' beliefs, knowledge, and practices and their backgrounds, experiences, and practice settings. Results of this study revealed gaps in EI SLPs' knowledge related to the cultural and linguistic influences on a child's developing language systems. Findings from Study 2 further revealed that EI SLP knowledge was positively related to the sociolinguistic context in which they practiced and the percentage of their caseload composed of DLLs and was negatively related to time since graduation. EI SLPs' use of best practices was positively related to the percentage of their caseload composed of DLLs. Study 3 was designed to understand EI SLPs' perceptions of facilitators and barriers to culturally responsive assessment practices. Results revealed the interconnected nature of facilitators of and barriers to culturally and linguistically responsive assessment practices, which included access to and quality of interpretation, access to materials and assessments, location of service delivery, policies governing assessment practices, composition of the EI team, and specific SLP and family characteristics. Taken as a whole, the results from these three studies suggest a need for continued knowledge development around the cultural and linguistic influences on DLLs' language development as well as the critical need for increased support related to the implementation of best practices across sociolinguistic contexts. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]