Research has identified multiple risk factors for the development of behavior difficulties. What have been less explored are the cumulative effects of exposure to multiple risks on behavioral outcomes, with no study specifically investigating these effects within a population of young people with special educational needs and disabilities (SEND). Furthermore, it is unclear whether a threshold or linear risk model better fits the data for this population. The sample included 2660 children and 1628 adolescents with SEND. Risk factors associated with increases in behavior difficulties. over an 18-month period were summed to create a cumulative risk score, with this explanatory variable being added into a multi-level model. A quadratic term was then added to test the threshold model. There was evidence of a cumulative risk effect, suggesting that exposure to higher numbers of risk factors, regardless of their exact nature, resulted in increased behavior difficulties. The relationship between risk and behavior difficulties. was non-linear, with exposure to increasing risk having a disproportionate and detrimental impact on behavior difficulties. in child and adolescent models. Interventions aimed at reducing behavior difficulties. need to consider the impact of multiple risk variables. Tailoring interventions towards those exposed to large numbers of risks would be advantageous.