A multistage tubular reaction system and method for preparing methylol derivatives of an aldehyde includes a tubular reaction system with a plurality of successive reactor stages provided with a formaldehyde containing feed stream. The system includes multiple feed ports for the staged addition of C2 or higher condensible aldehyde and/or base to the formaldehyde containing stream at a plurality of successive feed points to provide a production stream, which is progressively provided with additional reactants as the production stream advances through the successive reaction stages. Advantages include better temperature control and reduced byproduct formation.