For reasons of convenience I am importing data into a table, include a
dates, where all fields are text data types.

When I try to then query the database, converting a field into a
datetime (with convert) I get the following error:

"Arithmetic overflow error converting expression to data type datetime"

Is there something that I am doing wrong? How better could I convert a
text field into a date field for the purposes querying?

I am using SQL Server Express.

Thanks for any help,
Richard

User proper datatypes to avoid this type of errors

Try
Insert into table....
select cols from table where isdate(col)=1

Madhivanan