The row centres on moves to cut the number of principal teachers of individual subjects in the council’s five secondary schools and create so-called “faculty heads”, whose roles would cover a number of subjects.
Members of the Educational Institute of Scotland (EIS) union staged strikes in January and February over the issue.
A third set of strikes were called off earlier this month to ballot members on a revised offer from the council, but the union said it was “overwhelmingly” rejected.
EIS general secretary Larry Flanagan said: “EIS members in West Dunbartonshire are determined to stand firm against the authority’s plans to cut principal teacher posts in secondary schools.
“These changes would have a detrimental impact on the operation of secondary school departments, and a negative effect on learning and teaching activity in secondary schools.
“The EIS will have picket lines in place at all West Dunbartonshire secondary schools and will be holding a campaign rally today at Clydebank Town Hall, which we have invited representatives of all main political parties to attend.
“We will be asking each political party to share its views on these proposals and, in particular, the EIS will continue to urge the ruling Labour Party group in West Dunbartonshire to abandon these unpopular plans once and for all.”
A further two days of strike action are scheduled for April 26 and 27.