Despite the importance and usefulness of previous observational methodology investigations’ outcomes, there is no evidence about the creation or evaluation of a socioeducational intervention for parents in sport. Therefore, researchers do not have the possibility to apply a socioeducational intervention to their parental observations. This investigation was focused on the effects of the application of a socioeducational intervention with parents of 12 football teams in the U-15 years category in the Balearic Islands (Spain) during the 2016–17 season. Furthermore, six teams formed the control group (CG) and six constituted the experimental group (EG). This research was divided into three phases: (1) pre-test, (2) socioeducational intervention, and (3) post-test. The 12 matches recorded during the first phase and the 12 matches recorded during the third phase were observed and coded by trained observers using LINCE and POISE (parents’ observation instrument at sport events). Results showed a decrease in negative comments and an increase in positive comments during the matches, confirming the socioeducational intervention performed with that aim. This study suggests that the present socioeducational intervention demonstrates improvements on parental attitudes in grassroot football and, due to this reason, we encourage authors to use it and provide feedback.