Individual student success is influenced by the educational environment and student characteristics. One adaptation of the educational environment to improve student success is the introduction of continuous, or in-course, assessment. Previous research already identified several student characteristics that are related to student success as measured by student achievement, like previous achievements, motivation, self-efficacy and gender. The two facets are investigated in a group of first-year undergraduate Law students in the Netherlands, by examining the relationship of different types of continuous assessment and student characteristics with academic achievement. A questionnaire, measuring demographic information, self-regulation and motivational constructs, was completed by 94 students and their grades were requested from the student administration. Repeated measures ANCOVAs with assessment type as the within-subject factor identified that student achievement is not dependent on the type of continuous assessment. Students with higher high-school GPAs got higher scores across assessment types. Male students performed worse than their female peers in courses without continuous assessment, but in courses using any type of continuous assessment, this gender difference disappeared. Intrinsic motivation was a negative predictor of achievement in courses using writing assignments and mandatory homework assignments. Results from the current study indicate that continuous assessment may be a potent measure to improve male students' success by closing the gender achievement gap, and that students with high levels of intrinsic motivation do not benefit from continuous assessment.