Concepcion was elected to represent
Rizal in the
Philippine Constitutional Convention of 1971, during which he was an advocate for domestic manufacturers. Following the declaration of
martial law in 1972, during which he was noted for organizing his cell block to do daily tasks. the
National Citizens' Movement for Free Elections (NAMFREL) as its chair. He helped mobilize thousands of members through his slogan "it is better to light a candle than to curse the darkness" NAMFREL, particularly its volunteer wing known as the
Bantay ng Bayan, became known for monitoring instances of fraud and other irregularities and publishing results of the
1984 Philippine parliamentary election that contradicted the official results released by the
Commission on Elections (COMELEC). His tenure in the Aquino cabinet was marked by his launching of the "Yes, the Filipino Can!" movement to promote the Philippines' economic recovery after the Marcos dictatorship and his establishment of the One-Stop-Shop program for obtaining business permits and licenses. A message promoting the Yes, the Filipino Can! movement was included at the end of the 1991 comedy film
Juan Tamad at Mister Shooli: Mongolian Barbecue. A year later in 1992, he
ran for the position of senator, however achieved 29th place outside the winning circle of 24 candidates for that years elections. ==Later years==