MCS Age 9 months Sweep

Sweep details

Dates June 2001 to January 2003
Age 9 months
Achieved sample 18,818 (cohort members); 18,552 (families)
Respondents Parents
Fieldwork agency NatCen Social Research and Northern Ireland Statistics and Research Agency
Survey mode Face-to-face
Data access

Main dataset available via the UK Data Service [SN 4683]. Visit the UK Data Service website to access the data.


The start of the 20th century saw the beginnings of a new national cohort study, the Millennium Cohort Study, a multi-purpose longitudinal study designed to chart the circumstances, growth and development of 19,517 children living in 398 areas in England, Scotland, Wales and Northern Ireland.

Interviewers visited the cohort members’ homes and conducted face-to-face interviews with both resident parents. Parents also answered some questions via self-completion. Topics covered include family composition, housing and local area, parental education, employment and income, parental health, parenting activities and attitudes. Extensive information was collected about the new cohort member: ante-natal care, labour and delivery, breastfeeding, health, behaviour and development, childcare.

Permission was asked of the mother to link her hospital episode of delivery records and birth registration records to the MCS study data.


  • User guides
  • Questionnaires
  • Technical reports
  • Data notes
  • Additional
User guides

User Guide for MCS Sweeps 1-5

User guide for Sweeps 1-5 of the Millennium Cohort Study

Date published: 02/09/2020
PDF: 2,19 MB


Longitudinal Family File Guide

This guide provides information about the mcs_longitudinal_family_file which is an important dataset of the Millennium Cohort Study (MCS).

Date published: 02/09/2020
PDF: 166,27 KB


MCS Data Handling Guide

The Data Handling guide explains the data structures of MCS and provides solutions with different data handling strategies.

Date published: 02/09/2020
PDF: 1,14 MB


Handling missing data in the CLS cohort studies – User Guide

This user guide aims to describe and illustrate a straightforward approach to missing data handling, while detailing some more general considerations around missing data along the way.

Date published: 03/06/2024
PDF: 1000,62 KB


MCS 9 Months-Age 11 Guide to the Datasets (Eighth Edition)

Eighth Edition of MCS User Guide to the Datasets

Date published: 01/02/2014
PDF: 934,04 KB


MCS 9 Months User Guide to Initial Findings

Preliminary examination of findings in the first sweep of MCS

Date published: 01/01/2004
PDF: 1,51 MB


MCS 9 Months Guide to the SPSS Dataset

User guide to the SPSS dataset for MCS sweep 1

Date published: 01/05/2004
PDF: 349,33 KB


MCS 9 Months-Age 11 Guide to psychological and developmental inventories

Guide to the psychological and developmental inventories in MCS, covering 9 months old to age 11.

Date published: 05/01/2015
PDF: 741,77 KB


MCS 9 Months CAPI Questionnaire Documentation (2006)

CAPI questionnaire documentation for MCS sweep 1, with variables renamed in 2006

Date published: 01/03/2006
PDF: 532,01 KB

Technical reports

MCS 9 Months Technical Report on Sampling (Fourth Edition)

This is the fourth and final edition of a document that describes the design and sampling outcomes of the first sweep of the Millennium Cohort Study.

Date published: 01/07/2007
PDF: 677,83 KB


MCS 9 Months Technical Report on Instrument Development and Fieldwork

Technical Report on instrument development and fieldwork in MCS sweep 1

Date published: 01/06/2004
PDF: 10,78 MB

Data notes

MCS Geographical Identifiers

Geographic Identifiers in MCS

Date published: 01/06/2009
PDF: 45,77 KB


MCS 9 Months ESRC End of Award Report

Report on the ESRC funding for MCS sweep 1

Date published: 01/05/2001
PDF: 250,79 KB


MCS 9 Months Codebook and Edit Instructions

Details on the coding of the CAPI survey for MCS sweep 1

Date published: 01/02/2003
PDF: 1,04 MB


MCS Ethical Review and Consent

This note reports on the approach adopted to ethical review and informed consent for the various stages of the Millennium Cohort Study.

Date published: 01/02/2019
PDF: 7,98 MB

Contact us

Centre for Longitudinal Studies
UCL Social Research Institute

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London WC1H 0AL


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