The aim of this research was to investigate whether there was a predictive effect of the frequency of laboratory use of students, their academic success and attending various opportunities to learn science outside the classroom on the fifth and sixth grade students' scientific process skills performance (SPSP). Also, it was investigated whether there was a significant relationship between the students' SPSP and the grade level in which the concepts included in the test items were appropriate. The quantitative research methods were used in this study. Data were collected from 458 fifth and sixth grade students. Regression analysis was conducted to determine the effects of the frequency of laboratory use of students, their academic success and attending various opportunities to learn science outside the classroom on students' SPSP. As a result, it was determined that students' academic success was important predictor variables that affect the fifth and sixth grade students' SPSP. It was also determined that the frequency of laboratory use of students had an important predictive effect on students' causal scientific process skills performance (C-SPSP). Additionally, it was determined that various opportunities to learn science outside the classroom such as attending in science fairs and reading scientific journals had an important predictive effect on students' SPSP. Although, it was also determined that the students' SPSP differs according to the grade level, statistically significant relationship was not found between the students' SPSP and the grade level in which the concepts included in the test items were appropriate.