The study has been carried out within the subproject No. 8 “Latvian Language Acquisition” framework of the National Research Programme “Latvian Language”. The aim of this article is to analyse the results of Latvian language skills of the minority pre-school children who attend pre-school groups with Russian as the everyday communication language, the minority pre-school children who attend pre-school groups with Latvian as the everyday language, and Latvian pre-school children. The recordings of children’s speeches were made in Kurzeme pre-school education institu-tions during May and June of 2019 and 2020 before the children started to attend primary school. The findings obtained in this study are illustrated only with the results in vocabulary acquisition, taking into account that one of the most important tasks in learning a second language at pre-school age is vocabulary acquisition. Creating a conviction for beginning a new activity – communication in another language, not in the mother tongue, is of linguodidactic and psychological importance. Knowledge of a larger or smaller vocabulary is the basis for starting to speak a language. The study uses a picture-based conversation, with a maximum of 20 minutes spent in conversation with each child. The criteria proposed by Ingēra Tomme-Jukēvica (Tomme-Jukēvica 2018) have been used; they indicate the level of language skills (0 (insufficient level) – not showing or showing very minimal (<5%) knowledge and skills; 1 (low level) shows minimal (<25%) knowledge and skills; 2 (medium level) shows mediocre (>50%) knowledge and skills; 3 (high level) shows good (>75%) knowledge and skills. The article points out that each individual’s worldview forms with the mother tongue’s help and compares some striking linguistic lexical differences, paying particular attention to the comparative examples of Latvian and Russian languages. By referring to Latvian and Russian examples, the authors demonstrate that it may be necessary to divide the action expressed in one word in one language by creating a word group or even a phrase in another language. The Latvian language proficiency researchers should be aware that children with different native languages (Latvian or Russian) may have different worldviews, demanding additional actions of thinking and speech from the second language speaker. Therefore, second language acquisition at the pre-school age is an essential prerequisite for continuing bilingual studies or studies in Latvian at school. Observations made during the research in the National Research Programme testify that in pre-school education institutions, the process of education usually is interesting for children. However, as the analysis of the recordings of children’s speech in Kurzeme reveals, in those minority children groups where the everyday communication language is Russian and where Latvian is usually taught only two times a week for approximately 30–45 minutes, and also where the visual information in Russian dominates, insufficient skills of the state language and substantially worse experience of the Latvian language use have been observed. At the same time, it should be acknowledged that those minority children who attend groups with Latvian as the everyday language have learned Latvian sufficiently to continue education in the first grade of primary school. These children have not lost their native language, usually Russian, which they use actively at home. Therefore, they have the basis for several language acquisitions when they start learning at school. Learning Latvian as the second language requires optimization of this process in the pre-school education institutions, ensuring regular communication with the child in Latvian, and the use of appropriate methodologies in teaching activities. In this context, not only teaching and practicing Latvian lessons are particularly important, but also communication with other children and the possibility of talking Latvian with the staff of the pre-school educational institution. In accordance with earlier conclusions of linguists, the study conducted in Kurzeme shows that in the speech of pre-school children, independently of their mother tongue, nouns are dominating, but minority children attending groups with the dominant Russian language mostly use nouns in the nominative. Because of the task of preparing minority children for bilingual studies or studies in Latvian in the first grade, the authors of the article recommend ensuring bilingual communication on a day-to-day basis in minority groups of pre-school children.