UNICEF started the Multiple Indicator Cluster Survey series in the mid-90s, originally in response to the World Summit for Children. The goal of the first round of MICS was to measure progress towards mid-decade international goals. MICS1 was conducted around 1995 in more than 60 countries; however, data for the first round have not been released and only 12 reports are available online. Printed reports may be available through the library system.
There have now been six rounds of MICS, each including around 60 surveys in low-to-middle-income countries. While each round is different, the surveys are comparable, and topics commonly covered by the MICS include immunization, education, child and maternal health and HIV/AIDS. MICS also has focused on providing data for tracking progress toward the Millennium Development Goals (MDGS), particularly those related to health, education and mortality. Originally, rounds of MICS occurred every five years; with MICS4, the periodicity was increased to every three years.
Implementation of the surveys is usually done by a government organization, with UNICEF providing technical assistance and training. Mothers or caretakers of children in the household are typically the respondents, and populations covered are children and women ages 15-49. There is a household portion of the survey as well, and rounds sometimes include a questionnaire for men, ages 15-49. As with most large international surveys of this type, there are different modules that may or may not be used in a specific country such as salt iodization, child labor, and malaria. The childinfo.org site, where you can download MICS data and reports, has tables specifying which modules were used in which countries. Most MICS are nationally-representative; however, a few surveys have been done of specific populations. Also, in some cases, MICS surveys have been combined with other surveys, such as PAPFAM and DHS.
For more information on MICS, UNICEF has a range of resources on the childinfo.org site, including a page listing available datasets and reports from all rounds.