The majority of the world speaks more than one language, yet the impact of learning a second language has rarely been studied from a child's perspective. This paper describes monolingual children's insights into becoming bilingual at four time points: 2 months before moving to another country (while living in Australia), as well as 1, 6, and 12 months after moving to Germany. The participants were two monolingual English-speaking siblings (a male aged 7'8 years and a female aged 9'10 years) who subsequently learned to speak German. At each of the four time points, interviews were undertaken with each child using child-friendly drawing and questionnaire techniques. Three themes were identified: (1) the children's awareness of language competence, (2) inclusion factors, and (3) exclusion factors that influenced friendship formation. The impact of language ability on making friends was a dominant theme that arose across the four time points and was triangulated across data collection methods. The children made friends with others who had similar language competence in German, even though they were younger, and did not share the same first language. Age-matched peers who were more competent in German were less likely to be described as friends. Across all three themes, the playground was highlighted by both children as the key site where becoming bilingual most strongly impacted initiation and negotiation of friendships. Becoming bilingual impacted the children's friendship formation and socialisation opportunities with more competent language users.