This study explored the participation of Icelandic students with physical impairments, age 6-12, in regular schools. Critical influences on school participation were examined in order to provide an understanding of the various processes that interact to facilitate or hinder function in this context. The findings revealed that the students participated to a varying degree in different contexts in school. Some settings presented more challenges than others, typically open spaces with limited structures, such as the school playground and field trips. Potential facilitators and obstacles to participation were identified within the three dimensions of environmental, task, and child characteristics. Although specific child factors were associated with level of participation, setting characteristics strongly influenced student's participation. Structures to promote participation were often limited or inconsistently applied, thus, participation was sometimes obtained by chance rather than by design. The circumstances fluctuated for many students during the time of the study as environmental and task contingencies interacted with child characteristics to create different possibilities for participation over time. The dissertation makes a theoretical contribution to the debate on the construct of 'participation'. It adds to the literature on school participation by making visible the factors that typically act as facilitators or barriers to active involvement of students with physical impairments in school.