The contemporary parenting challenge of regulating children’s screen time became even more difficult during the coronavirus pandemic (COVID-19). The current research addresses the characteristics of this challenge and explores mothers’ perceptions regarding their children’s screen use, through two consecutive studies. Study 1 included 299 mothers of elementary school children, who were asked to complete questionnaires regarding their children’s screen habits. Mothers were also asked about their own attitudes towards screens, as parents, and about their personal feelings of frustration and guilt. Study 2 replicated this procedure among a new sample of 283 mothers who also completed validated scales assessing their sense of parental competence and authority style. Retrospective reports of mothers indicated that, during the lockdown, entertainment use of screens increased by 73% among 4th–6th graders and by 108% among 1st–3rd graders. Educational use increased by 86% in both age groups. Mothers’ guilt increased as well and was predicted by children’s entertainment use (but not educational use), after accounting for demographic variables and mothers’ attitudes. Other factors, such as parenting style and having at-least one child with a diagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD), were associated with entertainment use (regardless of the COVID-19 lockdown). Factors that were found to moderate the lockdown effect were mothers’ attitudes towards screens and parental confidence. The findings are discussed in the context of parents’ efforts to regulate their children’s screen use.